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Educational Product Educators Grades 5Ð8

Investigating the System PrecipitationPrecipitation “The Irrational Inquirer”

PROBLEM-BASED CLASSROOM MODULES

Responding to National Standards in: English Language Arts ◆ ◆ Science ◆ Social Studies Investigating the PrecipitationPrecipitation “The Irrational Inquirer”

Authored by: CONTENTS Mary Cerullo, Resources in Science Education, South Portland, Maine Grade Levels; Required; Objectives; Disciplines Encompassed; Key Terms; Key Concepts ...... 2 Prepared by: Stacey Rudolph, Senior Science Prerequisite Knowledge ...... 3 Education Specialist, Institute for Global Environmental Strategies Additional Prerequisite Knowledge and Facts ...... 5 (IGES), Arlington, Virginia Suggested Reading/Resources ...... 5 John Theon, Former Program Scientist for NASA TRMM Part 1: How are rainfall rates measured? ...... 6 Editorial Assistance, Dan Stillman, Truth Revealed after 200 Years of Secrecy! Science Communications Specialist, Pre-Activity; Activity One; Activity Two; Institute for Global Environmental Activity Three; Extensions...... 8 Strategies (IGES), Arlington, Virginia Graphic Design by: Part 2: How is the intensity and distribution Susie Duckworth Graphic Design & of rainfall determined? ...... 9 Illustration, Falls Church, Virginia Airplane Pilot or Movie Critic? Funded by: Activity One; Activity Two...... 9 NASA TRMM Grant #NAG5-9641 Part 3: How can you study ? ...... 10 Give us your feedback: Foreseeing the Future of ! To provide feedback on the modules Activity One; Activity Two ...... 10 online, go to: Activity Three; Extensions ...... 11 https://ehb2.gsfc.nasa.gov/edcats/ educational_product Unit Extensions ...... 11 and click on “Investigating the Climate System.” Appendix A: Bibliography/Resources ...... 12 Appendix B: Assessment Rubrics & Answer Keys...... 13 NOTE: This module was developed as part of the series “Investigating the Climate Appendix C: National Education Standards...... 15 System.”The series includes five modules: , , , , Appendix D: Problem-Based Learning ...... 17 and . While these materials were developed under one series title, they Appendix E: TRMM Introduction/Instruments ...... 19 were designed so that each module could be used independently. They can be freely Appendix F: Florida Weather Page ...... 21 downloaded at: http://www.strategies.org/CLASS.html Appendix G: Diagram ...... 22 June 2003 Appendix H: Glossary ...... 23

1 Investigating the Climate System: PRECIPITATION Investigating the Climate System PrecipitationPrecipitation “The Irrational Inquirer”

GRADE LEVELS Grades 5–8 coalesce nuclei/cloud nuclei TIME REQUIRED point/ Ten to twelve 45-minute class periods OBJECTIVES ● Students will analyze data and interpret information passive sensor/radiometer in order to make predictions. ● Students will utilize data to determine the intensity and distribution of rainfall. rainfall intensity/rainfall rate ● Students will apply satellite data to improve the scientific method safety of air travel. synchronous ● Students will analyze and global rainfall supercooled patterns. total integrated rainfall rate ● Students will apply various scientific methods total concentration in order to collect and interpret precipitation measurements. weather ● Students will apply various scientific methods in order to predict precipitation events. KEY CONCEPTS ● Students will examine long-range weather predic­ ● Clouds that produce , and therefore tions and compare them to archival satellite data. heavy rain and hail, are called cumulonimbus. These ● Students will study scientific data to determine how clouds often span an extremely large rainfall intensity and change vertically range. In strong thunderstorms, where the updrafts as well as horizontally. exceed 10 m/s, raindrops can actually be lofted up ● Students will investigate the effectiveness of using above the (where the temperature is the traditional scientific method in meteorological lower than 0°C). Some of these drops freeze to pro­ research. duce , while others remain in liquid ● Students will use their knowledge of TRMM to pro­ form despite the below-freezing temperatures— pose new instruments and satellite missions, which these are called supercooled water droplets. The will aid us in understanding and predicting changes combination of liquid and ice above the freezing in the ’s climate. level is known as the “mixed-phase layer.” In this ● Students will present their ideas to the class. region of the cloud, the ice particles and liquid water drops are colliding with each other. As a liq­ DISCIPLINES ENCOMPASSED uid drop collides with an ice , the liquid Meteorology, climatology, geography, language arts, attaches, or accretes, to the ice, enlarging the size of mathematics (data analysis, graphing skills), and the ice particle. Eventually, the ice particle with accreted liquid water (known as graupel) falls out of the updraft either because the updraft is weak­ KEY TERMS ening in that part of the cloud or the particle active sensor becomes too heavy. In some instances where the bright band updraft in the cloud is tilted with height, the parti­ climate cle can actually fall back into the main part of the

2 Investigating the Climate System: PRECIPITATION updraft lower down in the cloud. The particle may Because it is necessary to make assumptions about then be swept back up into the mixed-phase the size, density, and shape of the particles, as well as region, and grow again by . If this process the amount of emission coming from only the clouds, occurs a of , the graupel grows to these sensors provide a very indirect measure of pre­ become what we call hail. cipitation. Also, passive sensors can infer only the total ● As the crystals in cumulonimbus clouds fall accumulated depth of precipitation in the cloud, not and get close to the 0°C region, they stick together its vertical structure. The unique aspect of the TRMM and become large collections, or aggregates, of satellite is that it utilizes passive instruments as well as snow crystals. Subsequently, as they continue to fall, active instruments which can see the full vertical they start to melt so that a ring of liquid water forms structure of precipitation in the cloud, thus providing around the aggregate. Because liquid water reflects more accurate rainfall measurement. much more energy back to the radar compared to “There are many other climatically important measure­ ice, and because it only takes a small coating of liq­ ments obtained from satellites, such as the vertical uid water for the aggregate to look like a raindrop temperature structure of the , surface to the radar, the radar senses that it is seeing really temperature and , total ozone concentration, big drops. This is what produces the radar bright productivity, and biomass. These data are band (melting aggregates of snow flakes). As the available from NASA and NOAA (National Oceanic & particles continue to fall below the bright band, the Atmospheric Administration). large aggregate eventually melts into a large rain­ “The TRMM orbit limits its measurements to latitudes drop which, because of aerodynamic drag, eventual­ between 35°N and 35°S. TRMM does not acquire obser­ ly breaks up into smaller drops—which reduces the vations at higher latitudes. There are no other direct amount of power returned to the radar. The bright measurements of rainfall from satellites as accurate as band layer shows up clearly on TRMM radar images. TRMM. There are several satellites with passive ● An advantage of TRMM over other satellites is its sensors that observe every place on Earth two times ability to use radar to penetrate through clouds, each day, but because they are in Sun synchronous providing scientists with the three-dimensional orbits, they measure rain at the same local time at each structure of the rain formation. This is important place each day, a poor way to observe rain. Since rain­ since it is the distribution of latent heat within fall occurs in highly variable patterns, observations at clouds that affects the large-scale circulations of the each place should be made at various times through­ atmosphere. Recall that latent heat is released when out the day, as is done by TRMM. Also, passive sensors water changes phase: vapor to liquid and liquid to measure only the total integrated rainfall rate, but solid. Depending on the strength of the updraft and (like those on TRMM) can measure the vertical other properties of the surrounding atmosphere, profile of rain, which is important for understanding different clouds may release latent heat at different where the rain is forming, whether it is reaching the heights in the atmosphere. Forecast models need ground, and its effects on the stability and circulation this information on the distribution of latent heat of the atmosphere.” (inferred from radar structure) to accurately predict How passive sensors ( radiometers) and weather. active sensors (radars) work PREREQUISITE KNOWLEDGE A passive sensor (a radiometer) simply receives and measures the energy emitted by its target objects PART 1 (raindrops, in this case); TRMM radiometers are also How satellites observe weather and other sensitive to the energy emitted by the ocean/land sur­ phenomena from face, in the atmosphere, and scattering by According to Dr. John Theon, initiator and former pro­ ice particles. An active sensor (a radar, in the case of gram scientist for the TRMM satellite,“There are atlases TRMM) transmits energy and measures how much of of average monthly, seasonal, and annual rainfall over that energy is reflected back from the target objects. much of the Earth (except in the frozen regions of the Any object whose temperature is greater than ) measured by (satellites’) passive sensors. absolute zero emits energy.

3 Investigating the Climate System: PRECIPITATION Description of TRMM satellite image: condensation such that supercooled water will Hurricane Trail immediately freeze on contact with the surface of the aircraft. Because ice can weigh down the plane and alter its aerodynamic characteristics, the conse­ quences can be catastrophic . ● Rainfall intensity (rainfall rate) is measured by TRMM for various locations and times. Many such observations must be averaged for each area over a period of time to obtain a reasonable estimate of the total rain amount. Studies have shown that this is a valid technique of estimation. Maps of rainfall rates averaged over various time periods (say a month, a , or a year) can then be developed.

PART 3 ● The Scientific Method The scientific method is a series of steps that are used in scientific investigations in order to test a hypothesis. There are typically four steps: In the image above, the passing creates surface 1. Observe and describe a specific phenomenon. turbulence that stirs up cooler water from below the 2. Develop a hypothesis that explains what you surface of the sea. Had weather forecasters been able have observed. to see through the clouds, using TRMM satellite data, 3. Make predictions based on this hypothesis. which most other satellite sensors are unable to do, 4. Test those predictions by experimentation/obser- they would have been able to see the relatively cool vation; modify hypothesis based on results, if sea surface temperatures in the wake of Hurricane necessary. Mitch—and predict that the second hurricane would ● The next research mission to advance satellite obser­ weaken, because of the lack of warm water, and there­ vations of rainfall is called the Global Precipitation by become less of a threat to the regions in its path. Mission (GPM), now under study by NASA’s Earth A more accurate forecast might have prevented Science Enterprise. It will consist of up to eight small unnecessary evacuations and certainly calmed fears. satellites, each carrying a passive microwave sensor to observe rainfall, plus a single “flying ,” a PART 2 larger “mother” satellite that will carry a precipitation ● How temperature changes with varying height in radar to aid in calibrating observations from the the atmosphere. smaller satellites. This group of nine satellites will be ● How to read TRMM data. launched into polar orbits from which rainfall can be ● TRMM’s ability to “see” through clouds has impor­ observed every three hours anywhere on Earth. The tant implications, not only in understanding weath­ space agencies of Japan, China, Taiwan, Europe, and er, but also in helping pilots navigate through dan­ Brazil have expressed interest in participating in this gerous clouds. mission. The GPM satellites will be in a slightly high­ ● Ice and rain emit and reflect microwave energy dif­ er orbit than TRMM. At an altitude of 350 km, TRMM ferently. The TRMM satellite provides scientists with was able to use a smaller, less expensive antenna. images that show these differences. The new series of satellites will be launched into ● TRMM is the only satellite that provides images orbits that are about 450 km above the Earth. showing the vertical structure of rain. Although the antennas will have to be larger and ● Supercooled water can remain in liquid form at more expensive, the lower drag at higher altitudes temperatures as low as –40°C if there are no cloud will slow the rate of decay of the orbit, allowing the nuclei (condensation nuclei) upon which to coa­ satellites to stay in orbit longer, possibly 5–10 years. lesce. As it passes through supercooled water (TRMM was designed to last a minimum of three droplets, an airplane may serve as the nucleus for years, but is now expected to last 5–6 years.)

4 Investigating the Climate System: PRECIPITATION ADDITIONAL PREREQUISITE KNOWLEDGE SUGGESTED READING/RESOURCES AND FACTS Forpe, Will, editor. 1977. The Best of The Old Farmer’s ● Chart reading skills Almanac. New York: Jonathan David Publishers. ● Understanding of mean, median, and mode Lauber, Patricia. 1990. Seeing Earth from Space. New York: Orchard Books. Overview of how satellites ● collect data. ● Supercooled water droplets remain liquid from 0°C Ludlum, David. 1976. The Country Journal New England to as low as –40°C if there are no cloud nuclei upon Weather Book. : Houghton Mifflin. which to freeze. The Old Farmer’s Almanac. P.O. Box 520, Dublin, NH ● Map reading skills 03444. Phone: 603-563-8111. Web site: ● The first record of rain measurements occurred in www.almanac.com India in 350 B.C. Cerullo, Mary. 2000. Ocean Detectives: Solving the ● The first use of rain gauges occurred in 1247 in Mysteries of the Sea (and Teacher’s Guide). Boston: China. (See “Major Milestones in the History of Turnstone. Precipitation Research” on page 11 of A Global Williams, Jack. 1997. The Weather Book. Vintage Books. on Tropical Rainfall Measuring Mission [TRMM] for TRMM Web Sites: more rainfall measurement facts.) http://trmm.gsfc.nasa.gov (main TRMM Web site, ● Every year, The Old Farmer’s Almanac makes a gener­ with Breaking , Real-Time Data, and Maps of al weather forecast for the United States as a whole, Falling Water: Three Years of TRMM Data) as well as 16 regional weather forecasts. It predicts TRMM Hurricane Trail image—http://trmm.gsfc. weather information for each month. For example, nasa.gov/images_dir/mitch.html in 1998 it predicted: “Texas, January 1999: 5-Year TRMM Climatology—http://trmm.gsfc. Temperature 47° (2° above average); precipitation 0.5” nasa.gov/images/5-year_TRMM_climo.gif (1” below average). 1–9 Sunny, mild. 10–20 Sunny, cool. 21–31 Snow north, rain central, warm south.” There is Any additional, appropriate Web sites, such as: no scientific basis for such predictions other than —http://aqua.nasa.gov historical records which have skill only in the gross Goddard Space Flight Center Questions of the Week climatic sense. http://www.gsfc.nasa.gov/scienceques2002/ ● For the teacher—Activity One: Scientific Method 20021004.htm (p.10)—The purpose of this activity is for students National Oceanic and Atmosphertic Administration to think about the scientific method and how it http://www.noaa.gov applies to studying real-world Earth systems. The NASA’s Earth traditional application of the scientific method, http://earthobservatory.nasa.gov/Newsroom involving in controlled environments, The Weather Channel is not possible in this type of research. There are no http://www.weather.com/index.html independent/dependent variables and there is no http://phyun5.ucr.edu/~wudka/Physics7/Notes_ way to repeat an to test conclusions. www/node5.html http://teacher.nsrl.rochester.edu/phy_labs/ AppendixE/AppendixE.html 5-Year TRMM Climatology January 1998–December 2002

5 Investigating the Climate System: PRECIPITATION PART 1 How are rainfall rates measured?

MATERIALS Street map of the local community ● How have we traditionally collected rainfall (and other weather) data? 2–3 sheets of clear acetate that will cover the map Computers with Internet connection ● How has that data been used to Samples of The Old Farmer’s Almanac (optional, sample make forecasts? page provided in Appendix E), Florida, 1997 Reference books on weather

Truth Revealed After 200 Years of Secrecy!

SETTING THE STAGE Sheila wants the state climatolo­ satellite. The following is some somewhat shady inves­ gist to help her document how information she obtained from tigative reporter, Sheila well The Almanac’s past predic­ him: Wright Jonque, is pursu­ tions of precipitation events have correlated with actual events (in ing leads for an exposé Notes from an interview with to be published in the other words, how often are their Dr. John Theon on how satellites Apopular supermarket tabloid, The predictions correct?). Irrational Inquirer. Because her To provide an introduction for measure weather and other newspaper has been sued several her story, she first needs to phenomena from space: times for unsubstantiated stories describe how scientists collect written by Sheila, her editor now rainfall and other weather data, “There are atlases of average insists that she provide support­ in the past and present. She then monthly, seasonal, and annual ing evidence from an independ­ needs to understand how they rainfall over most of the Earth ent source before he’ll agree to predict rainfall. With this infor­ (except in the frozen regions of publish any more of her articles. mation, she will be able to write the planet) measured by (satel­ Sheila has found an unlikely (and her article. Because Sheila’s edi­ lites’) passive sensors. These sen­ unwilling) accomplice in the tor is hesitant to publish an arti­ sors do not directly measure state climatologist. She wants the cle written by her, she needs frozen precipitation [e.g., snow], climatologist to dig up facts for your help, as the state climatolo­ so they cannot provide truly her to corroborate a breaking gist, to ensure the information global precipitation observations. story, the first in a series titled provided in her article is accu­ (Although the TRMM radar can­ “How Do They Do That: rate. How would you help Sheila not detect most snow, passive Predicting Weather,” about the grasp the basics of meteorology sensors are sensitive to the scat­ reliability of the venerable The so she can research her story? tering from ice particles). There Old Farmer’s Almanac. Where would you go to get her are average monthly, seasonal, The Old Farmer’s Almanac has information to compare past and and annual global surface tem­ been predicting the weather present weather information? perature observations made by since 1792. It uses past rainfall About two weeks ago, Sheila satellite sensors. There are also patterns and many other data in took it upon herself to conduct average observations a secret formula to make fore­ an interview with Dr. John over the entire Earth obtained casts up to a year and a half in Theon, initiator and former from satellites. advance. Program Scientist for the TRMM

6 Investigating the Climate System: PRECIPITATION Part 1: How are rainfall rates measured?

“There are many other climatical­ times so poorly calibrated that radar), since rainfall amount is ly important measurements ob­ these estimates are not very accu­ highly variable from place to tained from satellites, such as the rate. However, calibration is only place, even across short dis­ vertical temperature structure of a small part of the problem. tances. TRMM measures rain the atmosphere, sea surface tem­ There are many difficulties in averaged over a whole area. perature and wind, total ozone using radar to estimate the actual Consider that a radar samples an concentration, ocean productivi­ rainfall on the ground; and this area 105–106 times larger than ty, and land biomass. These data includes measurements from the that of a rain gauge; if the precip­ are available from NASA and TRMM PR (Precipitation Radar). itation varies on a scale smaller NOAA.” Because the radar measures than what the radar can sample, “The TRMM (Tropical Rainfall above the ground surface and the radar estimate will be biased. Measuring Mission) orbit limits drops can evaporate before they On the other hand, radar does its measurements to latitudes hit the ground, not all of the give a better picture of the area between 35°N and 35°S. There radar beam may be sampling coverage of rain compared to are no other measurements of inside of the cloud. Part may be rain gauges.” rainfall from satellites as accurate outside, and most importantly, A good math problem for the as TRMM. There are several mili­ the distribution of raindrops students would be to calculate tary satellites with passive sen­ varies from one location to how much bigger an area the sors that cover every place on another, as well as from one time radar samples, compared to Earth two times each day, but to another. Since radars have to that of a rain gauge. Figure because they are in Sun synchro­ make assumptions about the dis­ that a rain gauge has an area nous orbits, they measure rain at tribution of raindrops in the of 0.1m and that the radar the same local time at each place clouds, which are often incor­ samples an area of about 1 km each day, a poor way to observe rect, the rainfall estimates are x 1 km. often way off compared to rain rain (since rain is notoriously “It is certainly true that The Old gauges. This brings up another chaotic in its day-to-day occur­ Farmer’s Almanac uses historical problem—the spatial variability rence). TRMM is an asynchro­ data to predict the coming year’s of rain and the sampling of a rain nous orbit, meaning that it weather. This will be a good fore­ gauge (point measurement) vs. observes a given place at varying cast if the weather follows previ­ the large area sampled by a radar times of the day each month. ous averages. However, there is (see the next paragraph below). Also, passive sensors measure little forecast information in his­ TRMM’s Precipitation Radar (PR), only the total integrated column torical averages if the weather is on the other hand, is the best rainfall rate (the sum of all rain not typical. Weather is a very calibrated, most stable radar in in the atmospheric column—not noisy variable, meaning that aver­ the world! In addition, PR’s view­ just what’s hitting the ground), ages do not describe it well ing geometry is far superior to but radars (like those on TRMM) except in general terms. Yes, in that of ground-based radars. By can measure the vertical profile general, it is colder in the way, radar is termed an active of rain which is important for than in , and yes, The sensor, not a passive one.” understanding where the rain is Almanac sometimes forecasts a forming.” “ use ground- storm accurately well in advance, “Meteorologists sometimes esti­ based rain gauges, usually locat­ but this is more by chance than mate area rainfall from ground- ed at weather stations, to meas­ by skill. Even the best scientific based radar observations (actual­ ure rainfall. Rain gauge measure­ forecasts for more than a week ly, the ments are not necessarily repre­ or 10 days in advance have only uses radar whenever possible), sentative of rainfall amount over a 10 percent skill, and the best but the weather radars are some­ a general area (as inferred from forecasters will tell you that.”

7 Investigating the Climate System: PRECIPITATION Part 1: How are rainfall rates measured?

PRE-ACTIVITY ● How can people use this information to predict ● Determine how you would make a rain gauge. rainfall? Collect the materials, make the gauge, set it up in your backyard, and write down your measurements Activity Three: Conclusion in a log. Be sure to include the date and time of Sheila has decided that for her to determine the relia­ each observation. bility of The Old Farmer’s Almanac, she will need to com­ ● After each member of the class marks the location pare data from The Almanac with data collected from of his or her home on a street map of the communi­ other resources. What kind of data would you look for? ty, cover it with clear acetate and make a map of Where would you go to obtain this information? rainfall amounts. What is the most effective way to Once you’ve obtained the appropriate data, analyze show the information on the map? Look for differ­ and interpret the information for Sheila. What does it ences in the amounts of rainfall. Can you think of mean? any factors related to environment or landscape Help Sheila write her article using the information you that may cause variations? Discuss your findings, have gained. Is The Old Farmer’s Almanac accurate? considering the statements made by Dr. Theon. Explain.

Activity One: How are rainfall rates measured? LANGUAGE ARTS EXTENSION As the state climatologist, your job is to help Sheila Each student should contribute a feature to produce a with her research for her article. Sheila is unfamiliar class edition of The Old Farmer’s Almanac. Examine a with the topic of meteorology, so she has requested copy and choose one section that you would write for that you help her in her background investigation. She the next issue. needs information on different methods of measuring rainfall. Determine what information Sheila will need MATH EXTENSION to conduct her research. Where would you, as the state The Almanac gives the time of sunrise in Boston, climatologist, go to get this information? What infor­ Massachusetts. Use the Time Correction Tables to find mation would you provide to her? Remember that the sunrise and sunset times (using Length of Day Sheila is required to provide supporting evidence for information) in your area. her article, so include resources used in the investigation. STATISTICS EXTENSION Further Discussion Question Explain what the evidence indicates about the reliabil­ Besides precipitation, other instruments also measure ity of The Old Farmer’s Almanac. The state climatologist, temperature, air , humidity, and wind flow. who supplied the satellite data, warns Sheila that she How might these help forecast rainfall/precipitation? really should examine more data before she writes her story. Sheila’s never used data before, so she thinks a ActivityTwo: How are rainfall rates predicted? few examples are more than enough to satisfy her edi­ In writing her article, Sheila has found she needs addi­ tor and the newspaper’s legal department. Discuss tional information on the following topics. First deter­ what you would consider to be a reliable sample size mine where you would get this information. Then con­ and how sample size affects students’ inferences. Use duct your research and determine what information to an example from the class; pick some characteristic give Sheila. that three students have in common (such as, last names beginning with S, or blue eyes) and then ● How is data collected and used to measure precipi­ extrapolate that to represent the whole class. Is that tation? Be sure to include information on satellites extrapolation accurate? and The Old Farmer’s Almanac. ● What are ground observations, weather records, and satellite observations, and what types of data do each provide?

8 Investigating the Climate System: PRECIPITATION PART 2 How is the intensity and distribution of rainfall determined?

MATERIALS ● Temperature and rainfall vary at various altitudes. Line drawing of cloud diagram (reproducible for students to write on—see Appendix G); pencil and paper; Internet access

Airplane Pilot or Movie Critic?

SETTING THE STAGE 30,000 feet. The ice coated the In his interview with Sheila, the private airplane was wings, he said, making the pilot claims to have hit turbu­ descending slowly plane so heavy that it started to lence at 30,000 feet as he toward an airport when fall rapidly. According to the descended through the clouds. it suddenly went into a pilot, warming temperatures at He states that it was at this time steep dive, much to the lower altitudes melted enough that they passed through an Adismay of its passengers and ice that he was able to regain area of supercooled water caus­ crew. After several minutes of control of the plane and land it ing ice to form on the wings, terror, the pilot was able to safely. subsequently causing the plane regain control and safely land Sheila Wright Jonque, investiga­ to drop 3,000 feet/minute. After the plane. tive reporter for The Irrational less than a minute, he says, the plane reached the bottom of As luck would have it, it was a Inquirer, has chosen this as the the bright band and the ice private jet carrying rock star second story in her series “How melted, allowing him to regain Damonna and her latest fiancé. Do They Do That: Predicting control, descend at a normal According to friends of the rock Weather.” In her interviews with rate of 1,000 feet/minute, and diva, the pilot left the cockpit the pilot and the passengers, safely land the plane. unattended while he joined his she has found discrepancies in celebrity passengers to watch their statements. Sheila has Can the climatologist back up the in-flight movie, “Airplane!” asked the state climatologist to the pilot’s claim by examining However, the pilot claims that help her obtain data from the TRMM satellite data for that he was at the controls through­ TRMM satellite to use in an date over the region where the out the flight and that the plane attempt to reconstruct the plane was flying? flew through an at entire event.

Activity One: What are we talking about? truth. She has determined three areas she needs help Before conducting any more research, Sheila has real­ in. Is her list below complete? If not, what other infor­ ized that she doesn’t fully understand the information mation does she need? she has gathered. As the state climatologist, she has ● The interior structure of clouds and how they form, asked you to brief her to bring her up to speed. Put ● A description of the bright band, and together a briefing for her, including all relevant back­ ● The importance of this information in flight ground information that will help her reconstruct the navigation. event and write the story. Once you are done with the research, make a diagram Activity Two: What happened? How do you find for Sheila that shows how the incident might have out if the pilot is telling the truth? happened. Sheila has asked you to help research the information necessary to determine whether the pilot is telling the

9 Investigating the Climate System: PRECIPITATION PART 3 How can you study rain?

Foreseeing the Future of Satellites!

SETTING THE STAGE determine what the next er satellites, such as the or her final article in generation of weather- TRMM satellite, and the her “How Do They observing satellites might be. types of questions scientists Do That: Predicting As the state climatologist, would like to be able to Weather” series, you’ve been asked for your answer in the future. FSheila Wright Jonque, inves­ help in understanding the tigative reporter, is trying to capabilities of current weath-

Activity One: The Scientific Method Observing and modeling the distribution of clouds and precipitation is important. Small changes in distri­ a. You have worked with Sheila before and are aware bution can lead to big changes in climate, although that she is unfamiliar with the scientific method. we still don’t fully understand how and why. For Before she continues with this investigation, you instance, changing the average base height of clouds would like to teach her about the scientific around the globe by 1000 feet would change the method, so she can use it to research, understand, global climate. and write her stories. What information do you a. Sheila has spoken with a sociologist (someone who need to provide for Sheila? studies human society), who believes she should b. How applicable is this method to real-world include information on the impact of rainfall pat­ research in meteorology? terns on human population in her article. As a cli­ c. Determine how meteorologists apply the scientific matologist, you are familiar with the effects of rain­ method to their real-world research. Are there dif­ fall patterns. What information do you need to pro­ ferences between the scientific method in labora­ vide Sheila? Why is this important for her article? tory versus real-world conditions? Describe these b. Working in small groups, study the two world maps differences. depicting TRMM coverage. Look at the data pre­ sented. What information is provided? Discuss what Activity Two: Why do we care about rainfall? you see, and any correlation between the data. Why did scientists choose the area of TRMM coverage MATERIALS that they did? ● Internet access c. How does the information you have just gathered, ● Map of the world—highlight the area of TRMM both the effects of rainfall patterns on human pop­ coverage (provide two maps for each group of ulation and the data presented by the TRMM maps, students working together) relate to each other? The central question that TRMM seeks to answer is “What is the global pattern of rainfall?”

10 Investigating the Climate System: PRECIPITATION Part 3: How can you study rain?

Activity Three: Future Studies SCIENCE EXTENSION a. In investigating the future of weather studies, you It is your task to invent the next generation of weath- and Sheila are working together to determine what er-observing satellites. Working in small groups, write questions scientists will need to answer. What back­ up a description of your satellite and what questions it ground information do you need to know? What will answer, so that Sheila can use the information to questions have scientists already answered? What write her story. After the groups’ ideas have been pre­ information would help meteorologists or climatol­ sented, as a class, choose three frequently mentioned ogists make better short and long-range forecasts? questions that need to be answered about rainfall and What instruments would be needed to collect this its impact on human society. data? b. What do you think Sheila’s final article should be SCIENCE/ART EXTENSION titled? What information would you recommend Use drafting paper to draw a design of an instrument Sheila include? or what the next generation of weather-observing satellites might look like.

UNIT EXTENSIONS Science/Geography Extension: Sheila Is Missing! Language Arts, Fine Arts, and Foreign Language Colleagues at the newspaper have heard rumors that the editors were trying to get rid of Sheila. Perhaps, Write up the conclusions of one of these problems they wonder, was she abducted by a band of Amazon using one of these styles: headhunters? They may be correct, because Sheila has ● The National Inquirer: Instead of quoting the subject, not been heard from since she sent an undated report write,“Friends say...”Vary the type style and point that torrential were assaulting the coastal region size. Write short sentences with many exclamation around the mouth of the Amazon . She managed points. to report back that average rainfall for the month ● The Wall Street Journal: Reference scientific studies, exceeded 20 inches. Examine the TRMM monthly rain­ quote authoritative experts—real or imagined— fall data and find any months where the mean rainfall from government and business. Use big words and exceeded 20 inches at the mouth of the Amazon River. small type. When was the last time she could have been heard ● A comic book: Use lots of artwork. from? ● Any periodical from another country, such as trmm.gsfc.nasa.gov/images_dir/avg_rainrate.html France or Spain. Write in the native language of that country.

11 Investigating the Climate System: PRECIPITATION APPENDIX A Bibliography/Resources

Forpe, Will, editor. 1977. The Best of The Old Farmer’s Journals: Almanac. New York: Jonathan David Publishers. AMS Newsletter, published by the American Lauber, Patricia. 1990. Seeing Earth from Space. New Meterological Society York: Orchard Books. Overview of how satellites ­ The Earth Scientist, published by the National Earth lect data. Science Teachers Association Ludlum, David. 1976. The Country Journal New England Geotimes, published by the American Geological Weather Book. Boston: Houghton Mifflin. Institute The Old Farmer’s Almanac. P.O. Box 520, Dublin, NH GSA Today, published by the Geological Society of 03444. Phone: 603-563-8111. Web site: America www.almanac.com Journal of Geography, published by the National Cerullo, Mary. 2000. Ocean Detectives: Solving the Council for Geographic Education Mysteries of the Sea (and Teacher’s Guide). Boston: Journal of Geoscience Education, published by the Turnstone. National Association of Geoscience Teachers Williams, Jack. 1997. The Weather Book. Vintage Books. , Macmillan Publishers Science, published by the American Association for the Web Sites: Advancement of Science TRMM Scientific American http://trmm.gsfc.nasa.gov Weatherwise, Heldref Publications Aqua http://aqua.nasa.gov Goddard Space Flight Center Questions of the Week http://www.gsfc.nasa.gov/scienceques2002/ 20021004.htm National Oceanic and Atmospheric Administration http://www.noaa.gov NASA’s Earth Observatory http://earthobservatory.nasa.gov/Newsroom The Weather Channel http://www.weather.com/index.html

12 Investigating the Climate System: PRECIPITATION APPENDIX B Assessment Rubrics & Answer Keys

Rubric: PARTS 1, 2, 3

SKILL Extensively Frequently Sometimes Rarely

Demonstrates ability to access relevant information at appropriate Internet sites

Collects/organizes data

Represents findings clearly on map/graph or written/oral explanation

Participates in class discussions/ presentations

Infers links between topic under investigation and weather/climate

13 Investigating the Climate System: PRECIPITATION Appendix A: Assessment Rubrics & Answer Keys

Cloud Diagram Answer Key: PART 2 50,000 ft.

30,000 ft. turbulence icing of plane supercooled water

25,000 ft. temp: -10°C

hail

15,000 ft. bright band: freezing layer temp: 0°C end of icing

hail end of hail formation

rain in clouds

cloud base: rain

GROUND temp: 20°C

Airplane Pilot or Movie Critic? If the plane dropped 3,000 feet/minute after ice formed on the wings at 30,000 feet, the plane would reach the end of the bright band (at 15,000 feet) in 5 minutes. The pilot claims it took less than a minute to reach the end of the bright band—therefore, the pilot was lying about how long it actually took him to regain control of the plane!

14 Investigating the Climate System: PRECIPITATION APPENDIX C National Education Standards

SCIENCE MATH Content Standard: K–12 Curriculum Standards for Grades 5–8 Unifying Concepts and Processes Standard 1: Mathematics as Problem Solving Standard: As a result of activities in grades K–12, all Standard 2: Mathematics as Communication students should develop understanding and abilities Standard 3: Mathematics as Reasoning aligned with the following concepts and processes: Standard 4: Mathematical Connections ● Systems, order, and organization Standard 10: Statistics ● Evidence, models, and explanation Standard 13: Measurement ● Constancy, change, and measurement National Council of Teachers of Mathematics. 1989. Curriculum and Evaluation Standards for School Mathematics p. 63–119. Reston, VA: Content Standards: 5–8 The National Council of Teachers of Mathematics, Inc. Science as Inquiry Content Standard A: As a result of activities in grades GEOGRAPHY 5–8, all students should develop: National Geography Standards for Grades 5–8 ● Abilities necessary to do scientific inquiry The World in Spatial Terms ● Understandings about scientific inquiry Standard 1: How to use maps and other geograph­ Physical Science ic representations, tools, and technologies to Content Standard B: As a result of activities in grades acquire, process, and report information from a 5–8, all students should develop an understanding of: spatial perspective. How to analyze the spatial organization ● Properties and changes in properties of Standard 3: of people, places, and environments on Earth’s ● Transfer of energy surface. Earth and Space Science Physical Systems Content Standard D: As a result of activities in grades Standard 7: The physical processes that shape the 5–8, all students should develop an understanding of: patterns of Earth’s surface. ● Structure of the Earth system Human Systems Science and Technology Standard 11: The patterns and neworks of econom­ Content Standard E: As a result of activities in grades ic interdependence on Earth’s surface. 5–8, all students should develop: Environment and Society ● Understandings about science and technology Standard 15: How physical systems affect human systems. Science in Personal and Social Perspectives American Geographical Society, Association of American , Content Standard F: As a result of activities in grades National Council for Geographic Education, and National Geographic 5–8, all students should develop an understanding of: Society. 1994. Geography for : National Geography Standards ● Personal health p. 143–182. , DC: National Geographic Research and Exploration. ● Natural hazards ● Science and technology in society National Research Council. 1996. National Science Education Standards p. 115, 143–171. Washington, DC: National Academy Press.

15 Investigating the Climate System: PRECIPITATION Appendix B: National Education Standards

ENGLISH LANGUAGE ARTS Standard 12: Students use spoken, written, and visual language to accomplish their own purposes (e.g., for Standard 1: Students read a wide range of print and learning, enjoyment, persuasion, and the exchange of nonprint texts to build an understanding of texts, of information). themselves, and of the cultures of the United States and the world; to acquire new information; to respond National Council of Teachers of English and International Reading Association. 1996. Standards for the English Language Arts p. 24–46. to the needs and demands of society and the work­ Urbana, Illinois and Newark, Delaware: National Council of Teachers of place; and for personal fulfillment. Among these texts English and International Reading Association. are fiction and nonfiction, classic and contemporary works. SOCIAL STUDIES Standard 3: Students apply a wide range of strategies Strand 3: People, Places, and Environments. Social to comprehend, interpret, evaluate, and appreciate Studies programs should include experiences texts. They draw on their prior experience, their inter­ that provide for the study of people, places, and actions with other readers and , their knowl­ environments. edge of word meaning and of other texts, their word Strand 8: Science, Technology, and Society. Social identification strategies, and their understanding of Studies programs should include experiences that textual features (e.g., sound-letter correspondence, provide for the study of relationships among science, sentence structure, context, graphics). technology, and society. Standard 4: Students adjust their use of spoken, writ­ National Council for the Social Studies. 1994. Expectations of ten, and visual language (e.g., conventions, style, Excellence: Curriculum Standards for the Social Studies p. 19–30. Washington, DC: National Council for the Social Studies. vocabulary) to communicate effectively with a variety of audiences and for different purposes. Standard 5: Students employ a wide range of strate­ gies as they write and use different writing process elements appropriately to communicate with different audiences for a variety of purposes. Standard 6: Students apply knowledge of language structure, language conventions (e.g., spelling and punctuation), media techniques, figurative language, and genre to create, critique, and discuss print and nonprint texts. Standard 7: Students conduct research on issues and interests by generating ideas and questions, and by posing problems. They gather, evaluate, and synthesize data from a variety of sources (e.g., print and nonprint texts, artifacts, people) to communicate their discover­ ies in ways that suit their purpose and audience. Standard 8: Students use a variety of technological and informational resources (e.g., libraries, databases, computer networks, video) to gather and synthesize information and to create and communicate knowledge.

16 Investigating the Climate System: PRECIPITATION APPENDIX D Problem-Based Learning

What is Problem-Based Learning? continually evaluate their contributions. Rubrics pro­ he Problem-Based Learning (PBL) model of teach­ vide a good guide for both teachers and students, to ing is a lot like it sounds; students learn by solving ensure that the students are continually kept on the Ta problem. While this occurs in all classrooms to a right track. different extent, the PBL learning model causes a dras­ tic shift in the roles of students and teachers. In tradi­ Why use PBL? tional teaching methods, the teacher acts as director Traditional teaching methods focus on providing of student learning, which is commonly passive. With students with information and knowledge. The PBL PBL, these roles shift. Students become active and model also adds “real world” problem-solving skills to responsible for their own learning, and the activity is the classroom. It teaches students that there is some­ student-centered; the teacher becomes more of a times more than one possible answer, and that they facilitator or guide, monitoring student progress. have to learn how to decide between/among these By using this model, the students gain information answers. through a series of self-directed activities in which the students need to solve a problem. These problems Students and PBL drive the learning process and are designed to help Students are broken up into groups and are pre­ students develop the skills necessary for critical think­ sented with a poorly structured, complex problem. ing and problem solving. Students learn that in the Students should have enough background knowledge real world, problems, and their solutions, are not to understand the problem, but should not be experts. always cut and dried, and that there may be different Any one, specific solution to the problem should not possible answers to the same problem. They also learn be evident. The students will need to determine what that as they continue to gain information, they need the problem is that they need to solve. Some organiza­ to readjust their plan. In other words, they must per­ tional questions they may ask themselves are: form self-assessment. ● What do we know about this problem? A PBL lesson starts with a problem posed directly to ● What do we need to know? the students. These problems are poorly structured to ● How/where do we get the information needed to reflect real world situations. Students (most commonly solve the problem? in small, cooperative groups) are then left to deter­ The next step for the students is to determine a mine what steps need to be taken in order to solve the problem statement. From the information given to problem. The teacher does not give the students the them in the problem, they should determine what information needed prior to the activity. However, the they need to know and then plan a course of action to teacher does need to make sure the students have get the information they need to propose a solution. enough prior knowledge to be able to interpret the In implementing this plan, they will have to gather problem and determine a plan of action. information to help them solve the problem. They will A key component of PBL is constant feedback. While need to be sure that the resources they use are cur­ the students are constantly assessing their work, and rent, credible, accurate, and unbiased. As information is in turn adjusting their plan, teachers also need to pro­ gathered and interpreted, they then apply their new vide continual, immediate feedback. Without feedback, knowledge, reevaluate what they know, and redeter­ students may be uncomfortable with this type of mine what they need to know to solve the problem. activity, because they do not know what is expected of Once all the information is gathered, interpreted, and them. Teacher feedback provides reinforcement for discussed, the group works together to propose a final student learning. Feedback should be an authentic, solution. performance-based assessment. Students need to

17 Investigating the Climate System: PRECIPITATION Appendix D: Problem-Based Learning

Benefits of PBL By using the Problem-Based Learning method, stu­ dents gain more than just knowledge of facts. They develop critical thinking skills while working in collab­ orative groups to try to solve a problem. In doing this, they learn how to: ● interpret the question/problem, ● develop a problem statement, ● conduct research, reevaluating prior knowledge as new knowledge is gained, ● determine possible solutions, and ● pick the best possible solution based on the infor­ mation they have gathered. By providing immediate student feedback, the stu­ dents can continually readjust their thinking, correct­ ing any misconceptions or errors before moving on. By using PBL, students become more familiar with “real world” problems. They learn that there is not always only one correct answer, and that they need to work together to gather enough information to deter­ mine the best solution.

The PBL Classroom When using the PBL model of instruction, it is best for students to work in small cooperative groups. The objective of this model is for students to work in a col­ laborative setting where they can learn social and eth­ ical skills to determine how to answer the question presented. Students are expected to regulate them­ selves while in these working groups.

PBL Assessment As the student groups work together to collect infor­ mation, they will need to constantly assess their own progress and readjust their plan. As they do this, they will need continual, immediate feedback from the teacher. When they become more comfortable with this model, they will learn to rely less on the teacher and become more independent. By providing the stu­ dents with the grading rubric, it will serve as a guide to ensure they are on the right track throughout the activity.

18 Investigating the Climate System: PRECIPITATION APPENDIX E TRMM Introduction/Instruments

Introduction to the Tropical Rainfall phere until it reaches a level where it is cooled to its Measuring Mission (TRMM) condensation temperature. Then the water vapor releases the energy (540 calories per gram) it ainfall is one of the most important weather and absorbed during the evaporation process. This “latent climate variables that determine whether heat” release can occur thousands of kilometers from Rmankind survives, thrives, or perishes. Water is so where the latent heat was originally absorbed. ubiquitous on planet Earth that we often take it for Water plays an additional critical role in weather and granted. Too much water results in devastating , climate: water vapor, it turns out, is the most abundant and the famine caused by too little water () is and most important greenhouse ! Greenhouse repsonsible for more human deaths than all other nat­ trap some of the energy given off by the Earth’s ural disasters combined. Water comprises more than surface in the atmosphere. Therefore, the distribution 75 percent of our bodies and as much as 95 percent of and quantity of water vapor in the atmosphere are some of the foods we eat. important in determining how well the Earth can emit Water is essential to life, as it nourishes our cells and the energy it absorbs from the Sun back into space. removes the waste they generate. Water determines Unless the Earth loses as much energy as it receives, it whether produce food, or whether they wither will warm up. If the Earth loses more energy than it from drought or rot from dampness. Water is essential receives, it will cool down. The distribution of water to our homes and factories, to our production of food, vapor in the atmosphere also affects cloudiness; and fiber, and manufactured goods, and to just about clouds play an important role in determining how everything else we produce and consume. Although much solar energy reaches the Earth’s surface, as well water covers more than 70 percent of the Earth’s sur­ as how much heat can escape to space. face, only about 3 percent is —and about Perhaps it is now obvious that water, in all its forms, 75 percent of that is inaccessible because it is locked plays a critical role in determining what we call weath­ up in and icecaps. er and climate. Our understanding of the complicated Another important aspect of rainfall, or any other interactions involving water is insufficient to permit us precipitation, is its role in redistributing the energy the to forecast, with much skill, weather beyond several Earth receives from the Sun. Evaporation of water from days and climate beyond a few months. Because the the Earth’s surface, condensation of water vapor into occurrence of precipitation is highly variable in both cloud droplets or ice particles, snow, precipitation, time and space, and almost three-fourths of the Earth’s runoff of the precipitation, and melting of snow and surface has no rain gauges because it is covered by ice constitute what is known as the water cycle, or the the , we have never been able to adequately hydrological cycle. Evaporation, the process of chang­ observe the global distribution of rain. Measurements ing water from liquid to gas form, absorbs 540 calories from rain gauges on islands and satellite images of of energy per gram of water; while simply raising the clouds have led to estimates of global precipitation. temperature of a gram of water one degree — But TRMM—the first satellite to measure precipitation without changing its phase— requires only one calo­ with the accuracy available from a radar in combina­ rie of energy. Thus, much of the Sun’s energy that tion with other remote sensors—represents a break­ reaches the Earth’s surface is used to evaporate water through in our ability to monitor precipitation on a instead of raising the temperature of the surface. The global scale. This is already leading to improved fore­ resulting water vapor is carried upward by the atmos­ casts, as shown on the next page.

19 Investigating the Climate System: PRECIPITATION Appendix D: TRMM Introduction/Instruments

which can be used to infer the three-dimensional distribution of latent heat in the atmosphere; ● provides information on storm depth; and without TRMM ● provides information on the height at which falling with TRMM snow or ice particles melt into rain.

Actual Visible Scanner (VIRS) The Visible and Infrared Scanner (VIRS) measures radi­ ance in five wavelength bands (from visible to infrared) emitted by clouds, water vapor, and the Earth’s surface. The intensity of radiation from a cloud corresponds with the brightness or temperature of the cloud, which in turn indicates the height of the cloud—brighter (colder) clouds are higher in altitude, and darker (warmer) clouds are lower. In general, high­ Hurricane Bonnie, August 1998: er clouds are associated with heavier rain. By compar­ 5-Day Forecasts vs. Actual Storm Track Improved forecasts can save money ($600K–$1M per mile of coast ing VIRS observations with rainfall estimates from TMI evacuated) and by more precisely predicting where the hurricane and PR, scientists are able to better understand the eye will be located at landfall. Source: Dr. A. Hou, NASA DAO relationship between and rainfall rate, and can apply this knowledge to radiation measure­ TRMM Instruments ments made by other weather satellites.

TRMM Microwave Imager (TMI) Cloud and Earth’s Radiant Energy System (CERES) The TRMM Microwave Imager (TMI) is a passive The Clouds and the Earth’s Radiant Energy System microwave sensor that detects and images microwave (CERES) measures the amount of energy rising from radiation emitted by water droplets, ice particles, and the Earth’s surface, atmosphere, and clouds. Clouds can the Earth’s surface. TMI detects radiation at five differ­ have both a warming and cooling effect on the Earth, ent frequencies, which helps to distinguish between trapping energy emitted by the Earth’s surface while rainfall, bodies of water, and land. Data obtained from blocking energy from the Sun. Similarly, water vapor this instrument is used to quantify the water vapor, also warms the Earth by trapping outgoing radiation, cloud water, and rainfall intensity in the atmosphere. but also condenses to form clouds that sometimes have a cooling effect. Data from this instrument helps Precipitation Radar (PR) scientists learn more about how the Earth distributes The Precipitation Radar (PR), an active sensor, is the the energy it receives from the Sun, as well as the first space-based precipitation radar. PR emits radar effects of clouds and water vapor on the overall tem­ pulses toward Earth, which are then reflected by pre­ perature and energy budget of the Earth. This informa­ cipitation particles back to the radar. By measuring the tion will help long-term climate models make more strength of the returned pulses, the radar is able to accurate predictions. estimate rainfall rates. Among the three main instru­ ments on TRMM, PR is the most innovative. Other Imaging Sensor (LIS) instruments similar to TMI and the Visible and Infrared The Lightning Imaging Sensor (LIS) is a powerful Scanner (VIRS) have operated in space before, but instrument that can detect and locate cloud-to- PR is the first radar launched into space for the pur­ ground, cloud-to-cloud, and intra-cloud lightning. The pose of measuring rainfall. Data obtained from this information gained from this instrument is used to instrument: classify cloud types and, together with other TRMM ● provides three-dimensional storm structures; instruments, to correlate lightning flash rate with storm properties, including rainfall rate. It’s also expect­ ● helps to determine the intensity and three-dimen- ed that the information provided from LIS will lead to sional distribution of rainfall over land and water, future advances in and .

20 Investigating the Climate System: PRECIPITATION APPENDIX F Florida Weather Page

21 Investigating the Climate System: PRECIPITATION APPENDIX G Cloud Diagram

50,000 ft.

30,000 ft.

25,000 ft. temp: -10°C

15,000 ft. temp: 0°C

GROUND temp: 20°C

22 Investigating the Climate System: PRECIPITATION APPENDIX H Glossary

active sensor (active system)—A remote-sensing sys­ each side can hold up to 4.48 ounces (139.3 grams) tem (e.g., an instrument) that transmits its own radi­ of water. At 104°F (40°C), the same cube of air can ation to detect an object or area for observation and hold up to 17.9 ounces (556.7 grams) of water. receives the reflected or transmitted radiation. Radar Relative humidity describes the amount of water is an example of an active system. 1 Compare with in the air compared with how much the air can hold passive sensor. at the current temperature. Example: 50% relative bright band—A narrow, intense radar echo due to humidity means the air holds half the water vapor water-covered ice particles at the melting level that it is capable of holding; 100% relative humidity where reflectivity is at its greatest. 2 means the air holds all the water vapor it can. At 100% humidity, no more evaporation can occur until —The average weather conditions in an area climate the temperature rises, or until the water vapor determined over a period of years. 1 leaves the air through condensation. Absolute climatology—Science dealing with climate and humidity is the ratio of the mass of water vapor climate phenomena.1 present in a system of moist air to the volume occu­ coalesce—The merging of two water drops into a pied by the mixture, that is, the density of the water 1 single larger drop. 2 vapor. condensation nuclei/cloud nuclei—A particle upon latent heat—The amount of heat given up or which water vapor condenses. It may be either in a absorbed when a substance changes from one state 6 solid or liquid state. 2 to another, such as from a liquid to a solid. dew point—The temperature to which air must meteorology—The study of the atmosphere and be cooled for saturation to occur, exclusive of air atmospheric phenomena as well as the atmos- pressure or moisture content change. At that tem­ phere’s interaction with the Earth’s surface, oceans, perature dew begins to form, and water vapor and life in general. 3 condenses into a liquid. 1 passive sensor (passive system)—A system using only graupel—A form of frozen precipitation consisting of radiation emitted by the object being viewed, or or ice crystals and supercooled water reflected by the object, or from a source other than 1 droplets frozen together. 2 the system. Compare with active sensor. hail—Precipitation composed of balls or irregular radar—Acronym for Detection And Ranging. An lumps of ice. Hail is produced when large frozen electronic instrument used to detect distant objects raindrops, or almost any particles, in cumulonimbus and measure their range by how they scatter or clouds act as embryos that grow by accumulating reflect radio energy. Precipitation and clouds are supercooled liquid droplets. Violent updrafts in the detected by measuring the strength of the electro­ cloud carry the particles in freezing air, allowing the magnetic signal reflected back. 2 frozen core to accumulate more ice. When the piece radiation/radiate—The process of giving off light, of hail becomes too heavy to be carried by upsurg­ heat, or other radiant energy. 4 ing air currents it falls to the ground. 1 rainfall intensity/rainfall rate—The amount of pre­ humidity—The amount of water vapor in the air. The cipitation of any type, primarily liquid, per unit time. higher the temperature, the greater the number of It is usually the amount that is measured by a rain water molecules the air can hold. For example: at gauge. 2 60°F (15°C), a cube of air one yard (0.9 meters) on

23 Investigating the Climate System: PRECIPITATION Appendix H: Glossary

scientific method—The scientific method is the way weather—The state of the atmosphere at a specific scientists get from asking a question to finding an time and with respect to its effect on life and human answer. The general steps involved are: activities. It is the short-term variations of the atmos­ • Defining the problem phere, as opposed to the long-term, or climatic, • Stating a hypothesis changes. It is often referred to in terms of brightness, • Making observations cloudiness, humidity, precipitation, temperature, visi­ 2 • Collecting data bility, and wind. • Analyzing data, making graphs

• Drawing conclusions based on the data 1 Looking at Earth From Space Glossary of Terms NASA EP-302 • Reflecting on your conclusions and determining 2 The Weather Channel Home Page: what you would do differently next time. 5 http://www.weather.com/glossary 3 Ahrens, C. Donald. 1994. Meteorology Today. St. Paul, MN: West Sun synchronous—Describes a satellite orbit in Publishing Company which the satellite passes over the same place on 4 USGS Glossary: http://interactive2.usgs.gov/glossary Earth, at the same time each day. For example, a 5 National Center for Ecological Analysis and Synthesis: satellite’s Sun synchronous orbit might cross the http://www.nceas.ucsb.edu/fmt/doc?/frames.html equator 12 times a day, each time at 3:00 p.m. local 6 USGS Water Basics Glossary: time. 1 http://sr6capp.er.usgs.gov/GIP/h2o_gloss supercooled water—Supercooled water is water that remains in a liquid state when it is at a temperature that is well below freezing. The smaller and purer the water droplets, the more likely they can become supercooled. 2 total ozone concentration—Refers to the concentra­ tion of ozone regardless of its form (dissolved or bound) in a sample. 6 turbulence—The irregular and instantaneous motions of air, which is made up of a number of small eddies that travel in the general . Atmospheric turbulence is caused by random fluctuations in the wind flow. It can be caused by thermal or convective currents, differences in terrain and , a frontal zone, or variation in temperature and pressure. 2

24 Investigating the Climate System: PRECIPITATION