UNIT VI: METEOROLOGY Review Book Pp

UNIT VI: METEOROLOGY Review Book pp. 113-138

This ppt has been modified (Aug.2012) from one created by Mr. Elliott from Fort Plain HS. Objectives #1 & 2

1. What is weather and how can it be described? 2. Explain the atmospheric variables: temperature, dewpoint, relative humidity, air pressure and wind. Meteorology: The study of our atmosphere, weather and forecasting.

meteorologist

Weather: Short-term conditions of our atmosphere. Most weather takes place in the troposphere and is driven by the unequal heating of the Earth by the sun. Unequal heating creates density differences in the atmosphere resulting in weather! P. 14 in ESRT’s Four Basic Weather Variables

Temperature Air Pressure

Weather

Wind Humidity Weather Variables

Temperature: The average kinetic energy of molecules in a substance. (measured with thermometer in oC, oF or K)

Warming

Cooler Hotter Temperature is not the same as heat! Heat: The total kinetic energy of all the atoms in a substance. (measured in calories or joules) Example: A teaspoon of boiling water has a higher temperature (is hotter) than a bathtub full of lukewarm water. However, the bathtub water has more heat energy because ______the total volume of moving water ______.molecules is much greater ( a lot of mild temperature vs a little hot) The air in Earth’s atmosphere is heated by the sun raising its temperature. Warm air rises and evaporates water while cool air sinks and condenses forming precipitation!

Temperature is affected by: Intensity and duration of sunlight, different surface materials (land vs. water), altitude, cloud cover & cold/warm fronts. Additional Temp Notes

 Highest temp  Usually 2-3pm  Lowest temp  Usually ½ hour before sunrise.  Coldest conditions  Clear and high pressure.  Warmest conditions  Partly cloudy and low pressure. Objective #3

 Relate dew point, air temperature, saturation and relative humidity and use the charts on ESRT p.12 to find them. Humidity: The actual amount of water vapor in the air. Dewpoint: The temperature at which water vapor in the air saturates the air and begins to condense.

Which temperature to the left is the dew-point temperature?

Without changing the 30 °C temperature, is When the air there anything else that temperature reaches the could change to raise dewpoint, the air is the 28% relative holding as much water humidity to 100%? as is possible and is said to be saturated. Humidity: The actual amount of water vapor in the air.

Look at the graph at the right to see the relationship between the amount of water the air can hold and temperature! Warmer the air, the more water the air can hold. Cold air has the capacity to hold less water.

Fact: There’s about 3,100 cubic miles of water vapor in the troposphere right now! (some as clouds, some as precipitation) Relative Humidity: The actual amount of water vapor in the air compared to the maximum amount possible at a given temperature.Both dewpoint and relative When the humidity are found in ESRT p.12. R.H. is 50%, the air is holding half of the water vapor it is capable of holding.

Lowest R.H.=0% 100 % means “Saturated” Highest R.H.=100% Air Temp= Dewpoint Temp

Note: Dew-point temperature is also called the “dew point” because dew or frost forms on exposed surfaces when the outside temperature falls to the dew-point. Water Vapor

Two things can raise the relative humidity to 100%: 1. Cooling the air down to the dew point 2. Adding more water vapor to the air (↑ dew point)  So as the difference between the dew point and air temperature decreases….  The r.h. increases and there is a greater probability of water vapor condensing to form precipitation. Measuring Dew point and Relative Humidity

Sling Psychrometer: Instrument used to find the relative humidity and dew point.

Wet Bulb Thermometer

Dry Bulb Thermometer

Slinging cools the wet bulb thermometer (evaporation cools) while the dry bulb just measures the regular air temperature. The amount of evaporation depends on the moisture content of the air. The lower the moisture content of the air, the more evaporation will occur from the wet bulb and the cooler the wet bulb temperature will be. The greater the difference between the wet and dry bulb temperatures, the drier the air. What’s true of the relative humidity, even after slinging, if the two thermometers are equal in temperature? It’s 100% or “saturated” ESRT p.12 ESRT p.12 Barometric or Air Pressure: The force exerted by the weight of air above and around us pushing down.

Lowest pressure (less air)

Highest pressure (more air) Fact: Earth’s atmosphere has a mass of 5,000,000,000 tons! Barometer: Instrument that measures air pressure. Units are usually in millibars (mb) or inches (in) of mercury. Mercurial barometer Aneroid barometer Home-made barometers are easy to make! ESRT p.13 Standard Atm. Pressure: The average air pressure when measured at sea level is: ______one atmosphere ______1013.2 mb of Hg ______29.92 in of Hg Isobars: Lines connecting points of equal air pressure on a weather map Pressure Map Wind: The horizontal flow of air

Winds are named for the direction that they come from!

Anemometer: measures wind speed

Wind vane: measures wind direction

What direction does a north wind blow?______south Wind moving southeast is called a ______northwest wind. Air’s ability to hold water vapor vs. temp.  The amount of water that air can hold is directly related to the temperature of the air. So the warmer the air, the more water that the air can hold.  So warm air has a greater water holding capacity than cool air.  Warm air is less dense and has more space.  For every 10oC increase, air can hold about twice as much water vapor. Important weather rule: Warm air has a higher potential to hold water vapor than cold air! This is exactly why some summer days can feel so uncomfortably humid! The warm air truly contains WAY more water vapor in it than could an equal amount of cold air.

Cool Fact: When air is saturated at 100% relative humidity it can’t get any more saturated! In other words, if you try to evaporate more water vapor into already saturated air it immediately condenses the extra back out into a liquid. As the air temperature changes, so does the dew point and relative humidity. As air is cooled to the temperature at which it becomes saturated (dew point) the relative humidity approaches 100%. Cooling the air causes it to contract and become more dense, decreasing the space available between air particles for water vapor.  As the difference between the dew point and air temperature decreases, the r.h. increases and there is a greater probability of water vapor condensing to form precipitation. Variations in pressure may be caused by three factors…..  Temperature  Altitude  Moisture (Humidity) Cold air has higher Warm air has lower pressure pressure Air Pressure vs. Temperature As air temperature rises its molecules of N2, O2, CO2, and water vapor move farther apart. Since the atmosphere is not like a container holding these gases in, they speed up and fly farther apart. The end result is warm air is less dense than cool air and has less mass per unit volume. Being less dense, warm air exerts less pressure and is lighter. (less weight of air pressing down). In contrast, cooling air contracts increasing its density and so is heavier and exerts more pressure on Earth’s surface. ppt

Increase temperature – decrease pressure PRESSURE

What type of relationship is this? Higher Higher pressure

Air molecules

Air Pressure vs. Altitude The force of gravity pulls most air molecules close to the Earth. This results in more air molecules and more air pressure near Earth’s surface and less air molecules and less air pressure far above the Earth. Water bottle pic Notice how pressure What type of decreases with altitude? relationship? Air molecule (28-32 amu) More dense

Water vapor molecule (18 amu) Less dense

Air Pressure vs. Humidity Fact: 1 water vapor molecule weighs less than an average molecule of air! This means air at 100% relative humidity has lots of the lighter water vapor molecules and less of the heavier air molecules. The result: Moist (humid) air is lighter, less dense, and lower in air pressure than dry air, which is heavier, more dense, and higher in air pressure. So what type of relationship? Must know .Winds move from high pressure to low factoid: pressure

Since temperature and pressure are inversely related, uneven heating of the Earth’s surface can create temperature and pressure variations that make the winds blow. Monsoons-seasonal winds

 Monsoons bring either very dry or very wet weather depending upon the season and their direction of flow. Seasonal temperature differences in large land masses such as Asia cause a disruption in the wind belts. Asia Winter Monsoons

 Winter, Asia is cold.  ↓Temp, ↑Pressure  Winds blow off land (↑Pressure) to low pressure over water  Bring dry air to India, Thailand, etc.  “Dry Winter Monsoons” Asia Summer Monsoons

 Summer, Asia is hot!  ↑Temp, ↓Pressure  Wind blows from water (↑pressure) to low pressure land.  Winds off ocean bring moisture.  “Wet summer monsoons” This monsoonal effect occurs in other places as well, but not to as great an extent. A similar daily effect may be experienced along the immediate coast. These daily effects are called land and sea breezes.

Image taken from www.valleywx.com on 9/8/12. Sea Breeze: Winds that blow from the cool water to the land. (daytime)

Sea breeze Land Breeze: Winds that blow from the cool land to the water (night).

Land breeze Winds and Breezes *Unequal heating of Earth’s surface (ex. day vs. night, sunny vs. cloudy) creates warm and cool areas. Warm air rises leaving a low pressure “void” while cool air sinks forming a high-pressure “bubble.” The movement of air from high to low pressure drives convection currents that result in horizontal winds and vertical currents!

Winds do not blow straight from Winds bend clockwise (right) high to low pressure because in the northern hemisphere wind direction is influenced by and counterclockwise (left) in the rotation of the Earth. the southern hemisphere.

This deflection of the winds is called the Coriolis Effect. Pressure & Wind Belts ESRT p.14 NON-ROTATING ROTATING EARTH EARTH

Low pressure Low pressure

GLOBAL AREAS OF HIGH (DIVERGENCE) AND LOW (CONVERGENCE) PRESSURE Global winds influence surface ocean currents: Objective #4

 How do clouds and precipitation form? Cloud Formation

Cooling of air as it rises leads to condensation This moisture can form clouds if there are surfaces or condensation nuclei present.

Microscopic particles of dust, ash, smoke, pollen or sea salt are common condensation nuclei.

This condensation occurs when the air temperature is cooled to the dew point temperature. Condensation vs. Deposition

•If the dew point temperature is above freezing, tiny droplets of liquid water form clouds. (CONDENSATION- Gas into Liquid) •If the dew point temperature is below freezing, water vapor solidifies directly into solid ice crystals. This is deposition, the phase change from gas to solid skipping the liquid phase. Condensation & Deposition on Earth’s Surface Both condensation and deposition can occur at the Earth’s surface. Condensation of water vapor in the air directly onto the Earth’s surface is called dew. When water vapor in the air undergoes deposition onto Earth’s surface, it is called frost.  Whenever air rises, the temperature of the air cools. Air can be forced to rise in a number of ways. Four common ways are…..

1. Heating 2. Convection Currents 3. Orographic Effect – air moving up over a mountain 4. Being forced up at a frontal boundary  When the rising air cools to the dew point, condensation or deposition occurs forming clouds made up of tiny droplets and/or ice crystals. Clouds: Liquid and/or solid water in the form of microscopic droplets

Golden Gate Beijing smog fog Thunderstorm clouds

Cumuliform:Puffy clouds, formed when air is pushed up vertically Stratiform: Low, layered clouds forecasting rain or snow soon. Formed when air drifts up at a low angle. Cirrus: High ice crystal clouds forecasting snow or rain in few days. Precipitation: All solid & liquid forms of water falling from the sky.

Rain, snow, sleet, freezing rain, hail & drizzle are all forms of precipitation.

rain sleet

snow

freezing rain hail Precipitation does not fall from all clouds because the cloud droplets are so small that the motion of the air keeps them suspended in the air. When the droplets or ice crystals coalesce (grow together) and become large enough to fall, precipitation occurs. As precipitation falls, it cleans the atmosphere by bringing down condensation nuclei and other materials suspended in the air. Cloud Formation

 How are clouds formed? By cooling in rising air.  As air rises, there is low pressure so the air expands which causes a temperature drop or cooling of the air. When the temp has dropped enough to reach the dew point, condensation begins to occur. This process of condensation releases energy into the air and forms clouds.  As the air descends down a mountain, the pressure increases and the air compresses. This compression causes the temperature to rise. When warm air rises, expands, and cools to the dew point, condensation occurs forming a cloud. If air sinks, it compresses and warms above the dew point evaporating the cloud.

Rising – Expanding – Cooling Air = Clouds Sinking – Compressing – Warming Air = No clouds Objective #5 and #6

5. Describe the 2 processes that add moisture and energy into the air. Give 4 ways the rate of evaporation can be increased. 6. What is vapor pressure and how is it related to altitude? at liquid’s surface

Greatest evaporation from here Transpiration

 Loss of water from plants through leaves.  Both the processes of evaporation and transpiration add moisture to the atmosphere. Since these processes go hand in hand, they are known together as evapotranspiration. How do moisture and energy get into the atmosphere? Both evaporation and transpiration require absorption of energy. Heat energy of sun is transferred from the atmosphere to the water vapor. The water vapor absorbs 2260 joules/gram of energy. This added heat energy is being converted to a kind of potential energy – stored energy.

So not only does evapotranspiration add water to atmosphere but also adds energy in the form of more energetic water molecules. Vapor Pressure

 Pressure exerted by water vapor within the atmosphere at any given location

 Vapor pressure is greatest near the pressure Vapor surface of the water. Altitude  As you go higher into the atmosphere, the vapor pressure decreases.  To increase vapor pressure, water must be added to the atmosphere by the processes of evaporation and transpiration.  The rate of evaporation depends on a number of factors such as ……  Temperature, heat energy, surface area, wind velocity, humidity Objectives #7 & 8

7. Explain the terms: latent heat, change of phase, potential and kinetic energy, melting, freezing, condensation, heat of fusion, heat of vaporization, specific heat 8. Explain and use the three formulas for heat gained and heat lost. Latent Heat- form of PE absorbed or released during phase changes

Latent heat changes are associated with changes in the potential energy. The temperature or kinetic energy of the molecules remains the same.  Heat energy is absorbed when the following phase changes occur:  solid to liquid to gas.  Heat energy is released when the following phase changes occur:  gas to liquid to solid.

 Review models/diagrams of phases! F Heat of Fusion- Freezing Fusion amount of latent heat involved in freezing or melting.  Involves: freezing and/or melting  Freezing: phase change from liquid to solid  Melting: phase change from solid to liquid  Involves: solid and liquid.

 Formula: Q=mHf  Heat of Fusion is 334 J/g  ESRT p.1 Heat of Vaporization- amount of latent heat involved in boiling (vaporization), evaporation or condensation.

 Involves: vaporization and/or condensation  Vaporization: phase change from liquid to gas  Condensation: phase change from gas to liquid  Involves: gas and liquid.  Formula: Q=mHv  Heat of Vaporization=2260 J/g  ESRT p.1  Which is larger Hf or Hv?  Hv is 2260 J/g  When condensation occurs in the atmosphere, the high amount of energy stored in the vapor during evaporation is released. This release of latent heat is the energy that intensifies and sustains violent storms. “Think hurricanes or big thunderstorms.” Temperature Changes (not Latent Heat Changes) Temperature- the measure of the average kinetic energy of the molecules of a substance.

During temperature changes, all the energy being absorbed or released changes the kinetic energy of the molecules. The potential energy or phase remains the same.  To calculate heat lost or heat gained during temperature changes, the following formula is used: Q=mcΔT Q is heat in joules(J) M is mass in grams(g) C is specific heat in (J/goC) ΔT is change in temperature (oC) Specific Heat Amount of energy needed to raise the temperature of 1 gram of any substance by 1oC

 The specific heat is different for different materials. See ESRT p. 1  Liquid water has the highest specific heat capacity among all naturally occurring materials on Earth.  The specific heat of water is 4.18 J/goC.

Image taken from http://www.ancientsuninc.com/images/ref ractants_files/Beaker1.jpg on 3/17/10 The higher the specific heat of a material, the more energy it takes to heat it and the longer the time it takes for it too cool.

Image taken from http://landscaping.savvy-cafe.com/wp-content/uploads/2008/01/pool-landscaping-rs.jpg on 3/17/2010 Objective #9

 Completely label a phase change diagram. Phase Change Diagram for H2O

 Label all on diagram on next slide. a) All three phases. b) Changes in latent heat and specific heat. c) Changes in PE and KE d) Melting, Freezing (solidification), condensation, vaporization (boiling), sublimation, deposition Narrated Video Animated Heat Curve “phase change” Objectives #10 & 11

10. Describe three ways that energy is transferred. How does this relate to density differences? 11. How are wind and pressure belts created? Use ESRT p.14 Conduction  Transfer of heat energy by contact (colliding) from one atom to another atom.  Conduction occurs in solids, liquids and gases.  However, conduction is most common in the solid phase because the particles are more compact and have the highest density.  This makes it easier for the particles to collide and transfer energy from one to another.  Examples:

Hot woodstove How does the spoon handle feel? Convection  Transfer of energy due to differences in density causing movement of molecules.  Convection is most common in gases & liquids.  The movement of gases and liquids due to convectional density differences can create a circulation pattern called convection currents or cells.  Examples: Radiation

 Transfer of electromagnetic energy through empty space.  Unlike conduction and convection which occur in the 3 phases of matter, radiation occurs in a vacuum or empty space such as the Sun’s radiation traveling to Earth through outer space.

ESRT p.14 Density Differences  A result of these density differences is that less dense (warmer) air will rise and be replaced by more dense (cooler) air creating convection currents.  Convection cells in the atmosphere are created by uneven insolation (heating from the Sun) and radiational cooling.  Radiational cooling- decrease in temp at Earth’s surface caused by energy radiating into space.  Radiational cooling in the polar regions results in sinking air which begins to move toward the Equator. WINDS AND CONVECTION CELLS CAUSED BY DIFFERENCES IN AIR PRESSURE

ESRT p.14

WINDS NAMED FOR THE DIRECTION FROM WHICH THEY COME  Convection creates wind & pressure belts.  Regions of low pressure are called zones of convergence. In these regions of low pressure, winds blow inward and rise.  Regions of high pressure are called zones of divergence. In these areas of high pressure, descending air diverges or moves apart.  Wind is a result of these areas of pressure and always blows from high to low pressure, in other words from regions of divergence to regions of convergence. This way solar energy is distributed over the whole Earth.  However, cold, dense sinking air in the polar regions does not move in a straight path to replace the warm, light air rising in the tropical regions. This is because the Earth rotates which causes these winds to follow a curved or deflected path.  This deflection is called the Coriolis Effect and deflects clockwise (right) in the Northern Hemisphere and counterclockwise (left) in the Southern Hemisphere.  The pressure belts and Earth’s rotation determine the general position and direction of the planetary wind circulation. What factors can change these general patterns?  Altitude, mountains, large bodies of water Objectives #12 & 13

12. Describe characteristics of air masses and the four air mass source regions. 13. Contrast cyclones and anticyclones. Air Masses Air mass: A body of air with similar temperature and moisture conditions. (wind & pressure too). 4 characteristics of air masses: ______temperature, ______humidity, winds,______air ______pressure.

Air mass characteristics are determined by the source region or geographic point of origin. cA or continental ESRT p.13 arctic air masses mP = maritime polar are very cold (humid and cool air) and dry mT = maritime tropical (humid and warm air) cP = continental polar (dry and cool air) cT = continental tropical (dry and warm air)  Air masses originating at high latitude are generally cold in temperature and called polar. Air masses that originate at even higher latitudes are referred to as arctic. If the source region is at low latitude, the air is warm and referred to as tropical. Air masses formed over water are moist and called maritime (m). If the air mass originates over land, it is called continental (c). The two most common air masses affecting New York are the cP (from Canada) & the mT (from the Gulf of Mexico) Cyclones Cyclones or low pressure systems. In the northern hemisphere air circulation is counterclockwise, inward towards the center and rises. The air rises because it is warmer, more humid and less dense. As a result this type of air mass is called a low pressure. Cyclones or low pressure often bring warm, rainy or unsettled weather. Anticyclones Anticyclones or high-pressure systems. In the northern hemisphere air circulation is clockwise, outward from the center and is sinking from above. The air sinks because it is colder, less humid and more dense. As a result this type of air mass is called a high pressure. Anticyclones or high pressure often bring cool and clear weather. Cyclone

Side view

Aerial View

Hints? Anticyclone

Side view

Aerial View

Hints? Objective #14

 Compare the 4 types of fronts. Be able to identify each on weather maps or construct a picture of each. Fronts – The boundaries between two air masses on ground.

Frontal surface- boundary up in the air  A front forms between 2 air masses with different temperatures. Along the front or frontal surface, the conditions are unstable and precipitation is probable. Air at the frontal surface is usually described as unstable because it is undergoing great change in its altitude, temperature and moisture content.

Precipitation occurs at the front because the air is rising and cooling, the relative humidity equals 100% and the dew point temperature has been reached. Basic rule of fronts

 Warm air rises up over colder air (less dense over more dense air).

•What determines whether a front is called a warm or cold front? •Depends on which one is pushing the other! Which is the dominant (bully) air mass Cold Front: The front edge of a moving cold air mass. ESRT p.13 LIFTING DUE TO THE APPROACH OF A COLD FRONT Cold Front Side View

Draw diagram. Cold Front Side View Steep slope of cold air

What cloud am I?

Why does the cold air hug the ground? Conditions of Cold Fronts: 1. Cold air pushes under warm 2. 10-15oC decrease in temp 3. Brief, heavy precipitation. 4. Possible Thunderstorms. 5. 180o change of wind. 6. Warm & humid before, cooler, clear & dry after (high pressure). 7. Precipitation occurs at the front 8. Moves through quickly. Leading Edge of Cold Front Which direction is it moving?

Satellite View of Cold Front Can you locate Long Island, NY? Warm Front: The front edge of a moving warm air mass. ESRT p.13 Warm Front – Side View Note the progression of cloud types as the front approaches

Warm Air

Cold Air Warm Front – Side View

Draw diagram. Cirrus

Stratus

Nimbo Stratus As a warm front approaches the clouds get lower in altitude Conditions of Warm Fronts:

1. Cooler before, warmer & more humid after 2. Precipitation occurs in front of the front 3. Slow moving, sometimes several days. 4. Long, gentle precipitation 5. Thin, stringy clouds (cirrus,alto,stratus) 6. Possible temp inversion 7. Sleet, glaze possible. Stationary Front: •Exists when 2 air masses of different characteristics (hot&cold) are not moving. •No “bully”, cold & warm air mass are equal. •Weather conditions similar to a warm front. ESRT p.13 Winds often move sideways relative to each other

Warm air mass Cold air mass Stationary Fronts Bring: 1. Unpredictable precipitation 2. Unpredictable wind direction 3. Can remain for days on end! Occluded Front: •Interface between a ____cool and _____cold air mass. •Occurs when a _____cold front overtakes a _____warm ESRT p.13 front, lifting the warm air mass off the ground.

Occluded fronts often produce ______heavy precipitation. Objective #15

 Describe characteristics of a middle latitude cyclonic storm. Middle Latitude Cyclonic Storm Low pressure Aerial View Side View

Early On

Later as storm has progressed Note the cold front lifting the warm air mass up Middle Latitude Cyclonic Storm

 Distinguishing Characteristics: 1. Warm and cold fronts usually come out of low pressure center. 2. Warm front leads cold front, cold moves faster 3. Two periods of precipitation, if not occluded. 4. In middle North latitudes (USA) storms generally move towards NE. Occluded Fronts Bring:

1. Cloudy skies 2. Chance of precipitation including t-storms 3. Not much temp. change on the surface (all the action is above) What are the actual names of the isolines below?

Where did the mT air mass probably originate? Where did the cP air mass (north or Lake Ontario) probably originate? Draw the front symbols on the map below

Note cP how the Top View lettered locations mT below match up to the letters Side View above?

Where do the mT and cP air masses go? Objectives #16 & #17

16. Use ESRT p. 13 to explain a weather station model and describe information found on weather maps. 17. How is isobar gradient related to windspeed? WEATHER FORECASTING

Meteorologist: ______scientist who studies and forecasts weather Forecasting the weather involves putting together all of the pieces we’ve learned so far. We need to analyze the data and interpret what the data is telling us, then use forecasting skills to make the right predictions.

Field Values: ______such as temperature, air pressure, relative humidity and ______dew point shown on weather maps with isolines

Isolines: ______Lines connecting points having equal field values

Isotherms: ______lines connecting points of equal temperature Isobars: ______lines connecting points of equal air pressure KEY FEATURES OF WEATHER MAPS 1. ______Station models 2. ______Cyclones (low pressure systems) 3. ______Anticyclones (high pressure systems) 4. ______Fronts 5. ______Isolines (normally isobars) Gradient: ______Change in value from one point to another An example of gradient is how steep a hill is, i.e., how much does its altitude change over a given distance?

The formula to calculate gradient is on the front cover of the ESRT. The two types of gradient we normally look at in weather are ______andtemperature ______.barometric pressure They are both calculated in the same way.

You can easily determine temperature and pressure gradients on weather maps. If the isolines are close together, that indicates a steep gradient. If they are widely spaced apart, then you have a shallow gradient. IMPORTANT: The pressure gradient is directly related to windspeed. The greater the difference between a high and low pressure center and the less distance between the pressure centers, the faster the wind speed. Fastest winds because isobars are closest

Slower winds because isobars are far apart. Weather Station Models ESRT p.13

 Weather Station Models indicate the weather at a location on a weather map. Station Models do not include labels so that many of them can be placed on a single map. The Weather Station Model

Draw a Station Model

Get accompanying notes here

196 Insert a decimal point to the left of the last digit 19.6 Put a “9” and a “10” in front of the result 919.6 1019.6

Test the results against the range of normal atmospheric pressures

919.6 is below the range of normal pressures…. REJECTED!

1019.6 is within the range of normal pressures…. ACCEPTED! Coded pressure 196= 1019.6 mb Decode these coded pressures: 002 993 280 000 1000.2 999.3 1028.0 1000.0

Back to the Station Model How to encode pressures

1013.5 Remove the decimal point 10135 Report the last 3 digits 135

Pressure 1013.5 = 135 encoded pressure

Encode these pressures: 1032.7 987.3 1012.2 1000.1

327 873 122 001

Back to the Station Model Back to Decoding Pressures

©S. Kluge 2007 The Barometric Trend + 19 / + means “Higher now than it was 3 hours ago” (- means “Lower now than it was 3 hours ago”) 19 means the pressure has changed by 1.9 mb

/ means the pressure is currently rising ( \ means the pressure is currently falling)

What was the pressure 3 hours ago? Here?

1017.7 1003.5

Back to the Station Model

Temperature= 45F Dewpoint= 32F Wind NE at 20 knots Overcast Visibility= 1.5 miles Rain Showers Pressure Now= 997.3 mb Pressure 3 hrs. ago= 1000.2mb Barometer Falling Precipitation in last 6 hrs.= .53 in.

Back to the Station Model

 Describe weather patterns and information that is used for making forecasts. Synoptic Weather Map ______.Gives a “bird’s eye” view of the weather Studying synoptic weather maps allow scientists to make short term predictions of future weather conditions. Forecasters generally watch the direction a cyclone has been moving and assume the system will continue to move in that direction and at roughly the same speed. This is called the storm track. This can be calculated by measuring the distance the storm has traveled and dividing that distance by the time it took to go that far. Over North America, storm movement is generally predictable. Tropical air masses generally travel in a northeast direction and polar air masses generally move southeast because the prevailing westerly winds blow from west to east. Note the direction of our prevailing winds. Jet Stream – Strong wave-like currents of winds in upper troposphere that can travel as fast as 300 km/hr. Storm Track – steered by the jet stream Modern day meteorologists use data to determine the path and speed of a storm to predict changes ahead of the storm. Meteorologists use records of past weather and computer analysis to predict weather conditions as a probability of occurrence. This has allowed weather forecasters to make short term forecasts (1-3 days) with good accuracy. It is far more difficult to make forecasts extending a week or more in advance. Modern Forecasting Since weather variables are related in a complex way, accurate weather prediction is also complex. The increasing reliability of the day-to-day weather forecast can be attributed to ground observations, radar and satellite imagery. However, even with this technology, it is unlikely that accurate weather predictions will be made for a week or more in advance because a small, unexpected disturbance may have world wide unexpected effects on the weather. Objective #19

 Describe hazardous weather conditions like thunderstorms, hurricanes and tornadoes. Tell where and when each are likely to occur and safety precautions that should be taken for each. SEVERE STORMS (THUNDERSTORMS/TORNADOES/HURRICANES/WINTER STORMS) Thunderstorms: •Transient, sometimes violent storm of thunder and lightning. How form? form where moist, unstable air is forced upward abruptly What are dangers with thunderstorms? • Lightning, flooding from heavy rain, hail, damaging winds and tornadoes are all possible from strong or severe thunderstorms. Of the above, lightning kills more people in U.S. What do you do if caught in a thunderstorm? •Seek shelter indoors or stay in your car. •Avoid windows & electrical appliances/outlets. •If outside, avoid tall trees, buildings, etc. T-storms have short durations. Hurricanes Tropical cyclone with winds in excess of 75 mph or 119 km/hr

 Occur in summer, June- Sept.  Form in low latitudes (closer to equator) over warm, tropical water. Energy released by condensation fuels the storm. Hurricane: Hurricanes go through life-cycles, starting as ______,tropical depressions then become ______,tropical storms and finally become ______.hurricanes Their designation is dependent on their top wind speed. Compared to middle latitude cyclonic storms, hurricanes have lower pressure and greater intensity. Hurricanes normally have an eye at their center which is an area of surprisingly clear and calm weather. The clouds surrounding the eye, however, are where the winds are the strongest and blow out.

Hurricane Francis – September 2004 Hurricane: Tightly packed isobars indicate strong winds. Most destructive of the severe storms due to large size and paths which may cover a thousand miles. Most damage is done by water in coastal areas.

Hurricane Katrina 2005

Storm Surge

The most severe hurricane damage is from storm surges… •Hurricanes gain energy and pick up moisture over warm water. Hurricanes die down over land or cold water. Average life span of a hurricane is 9 days.

Hurricane Irene 2011: Flooded street near Binghamton, NY

Image taken from www.wbng.com on 9/8/12. Hurricane Isaac August 2012  What to do if a hurricane is headed your way?  Evacuate from coastal or low lying areas.  Board up windows. Secure outside objects for strong winds.  Sandbags to limit flooding of property.  Be prepared to live several days without electricity, transportation or fuel. Tornado Wall cloud

Funnel cloud

Tornado: ( most violent )______powerful but small tower of swirling winds ______.that form within a thunderstorm Their distinct funnel shape makes them easy to recognize. The center of a tornado is called the vortex. Winds move counterclockwise around the vortex and inside the vortex can reach speeds higher than 600 km/hr and move upward. Anatomy of a tornado Tornadoes form when warm, moist (mT) air masses from the south and cool, dry (cP) air masses from the north collide. Tornadoes have occurred in almost every state in the country but are most common in the center of the U.S. (Great Plains and Gulf States) which is known as “Tornado Alley”. Tornadoes are most common in the late afternoon during the spring and early summer when temperature differences are the greatest. Small sized tornadoes are called twisters. A nominee for the Darwin Award! Where’s Toto? How do they measure tornadoes?

Fujita Scale: describes Enhanced Fujita intensity and possible Scale damage associated with different strength tornadoes. F-0 is the weakest tornado and F-5 is the strongest. Tornadoes can be from meters to a mile wide and can travel at a forward speeds of 40-60 km/hr.  What to do if caught in a tornado?  If inside, go to lowest floor possible. basement? Stay near interior walls or closets.  If outside, get out of automobiles, lie flat in a ditch or depression and cover head with arms.  No time to evacuate! Winter Storms: ______low pressure systems bring together dry, cold, northern ______.air and warmer, moisture-laden southern air The greatest risk from winter storms are ______,heavy snow ______,very cold temperatures and ______.high winds There are two unique types of winter storms important to people in New York. Lake Effect Storm: snowfall at a specific location is ______intensified because of its nearness to a large body of water. As cold air passes over a large body of relatively warmer water, the air ______warms and picks up moisture. Once the air moves past the water body, it ______cools once more. No longer able to carry the moisture, it is dropped in the form of snow.

Lake effect snow storms are localized events. Only areas ______downwind from and relatively ______close to the water body are effected by lake effect. See diagram on next page. Winds wrapping around the low pressure center in a counter-clockwise direction is bringing cold, Canadian air over the relatively warmer waters of Lake Ontario and Lake Erie. Once the air gets over the cold ground of New York State, the air cools and drops its moisture load. Notice the tightly packed isobars indicating strong winds. This is a real “white-out” or blizzard! LAKE EFFECT SNOW Nor-easter storm track

Nor-easter: slang term or local name for ______low pressure system moving ______up Atlantic coast, causing northeast winds that carry a lot of moisture in ______off from the Atlantic Ocean; more intense closer to the ocean WATCHES AND WARNINGS (Severe Thunderstorm, Tornado, Hurricane or Winter Storm) Watch: ______storm conditions are possible within 36 hours; be prepared to ______evacuate if told to; stay informed of changing conditions.

Warning: ______storm conditions are expected within 24 hours; when told to ______do so, evacuate immediately! Q: How much training is needed to be a meteorologist? What are the main duties of the job? A: Becoming a meteorologist generally requires four years of college that includes a great number of mathematics and science courses. Some people get into meteorology by going into the armed forces without a college degree and being trained to do various kinds of work at weather stations. Many of these men and women take college courses in the service. The work done ranges from observing the weather, making weather forecasts for the National Weather Service, private companies or television stations to helping conduct meteorological research. Most researchers, however, have advanced college degrees. All in all, to become a meteorologist you have to be good in science. The American Meteorology Society has answers to many questions about meteorologists and career in meteorology. You can find out more by going to the Society's Information and resources for students page.