DOCSLIB.ORG

Surface Temperature Inversions and Spraying FACT SHEET

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Surface Temperature Inversions and Spraying FACT SHEET reprinted July 2014 surface temperature inversions and spraying FACT SHEET NORTHERN, SOUTHERN AND WESTERN REGIOns THe infLuenCe Of SurfACe TemPerature inverSiOnS On SPrAy OPeratiOnS in cooling night conditions airborne pesticides can concentrate near the surface and unpredictable winds can move droplets away from the target. understanding weather conditions can help spray applicators avoid spray drift. warm air Key points cool air Where surface temperature inversion conditions exist it is unsafe for Top of the inversion spraying due to the potential for spray drift. Spray applied at dawn, dusk and Height during the night is likely to be affected by a surface temperature Night profile inversion. Day profile During surface temperature inversions, air near the ground lacks turbulence. This can lead to airborne pesticides remaining at high concentrations in the air at or near cool warm the surface. Temperature The direction and distance that pesticides can move in the air close FIGURE 1 Typical vertical temperature profiles for a point in time to the ground is very hard to predict during the night and day. At low levels, the day profile typically cools when surface inversions exist. with height and the night profile typically warms with height. Little change occurs at elevated altitudes. SOurCe GrAeme TePPer During daylight hours the temperature of airborne droplets and helps to drive many of When this occurs close to the ground it is the soil surface gradually increases. Air in them back towards the ground. called a surface temperature inversion. contact with the ground also warms (figure When this dilution occurs, a safe buffer in a surface temperature inversion 1). in this situation the air temperature distance between the sprayed area and the point where the temperature stops normally becomes cooler with height. potentially sensitive areas downwind from increasing and begins to decrease is the top Wind speeds during daylight hours will the application site can be estimated. of the inversion layer. generally be more than 3 to 4km/h and the surface temperature When a strong surface temperature air movement across the surface will tend to inversions inversion has established, it can act like be turbulent. a barrier, isolating the inversion layer from inversion conditions can differ significantly the normal weather situation, especially the Turbulence close to the ground causes the from the broader forecast weather patterns. air to mix, due to the rolling motion of the normal wind speed and direction (figure 2). During the night the ground loses heat and air across the ground surface. mixing is also the low-level air cools (figure 1). This results Surface temperature inversion conditions are caused by thermals, which interrupt airflow. in air temperature increasing with height and unsafe for spraying as the potential for spray This mixing of the air assists in diluting the temperature profile is said to be inverted. drift is high. Level 1, Tourism House | 40 Blackall Street, Barton ACT 2600 | PO Box 5367, Kingston ACT 2604 | t +61 2 6166 4500 | f +61 2 6166 4599 | e [email protected] | W www.grdc.com.au Page 2 warm air typical wind profile inversion wind profile cool air longer arrow equals greater wind strength Height Inversion layer Calm or light winds so long as local winds warming land cooling land do not develop FIGURE 2 Air movement under a surface temperature inversion differs from a typical wind profile (left). Surface winds de-couple from the surface, accelerate and flow over the inversion. Within the inversion, winds are typically light and often drain down slope, regardless of the overlying wind direction. Under an inversion the shape of the landscape also influences the direction in which airborne droplets will move (right). SOurCe GrAeme TePPer under a surface temperature inversion: research supported by the GrDC is to the ground to become cooler than further investigating the development and the air above. The three main reasons air movement is much less turbulent so experienced in broadacre agriculture are: the air does not mix in the same way as implications of temperature inversions in relation to spray application. during the day; 1. radiation inversions (created airborne droplets can remain When and why do surface by radiation cooling) concentrated in the inversion layer for temperature inversions long periods of time; radiation inversions can form at any time occur? during the night when wind speed is less the direction and distance pesticides than about 11km/h and cloud cover does movement is very hard to predict; Surface temperature inversions usually not severely restrict surface cooling. in develop overnight and can persist well into the movement of airborne droplets will calm and clear sky conditions they may the next day. vary depending on the landscape; and form just before sunset. Once the sun has droplets or their remnants can move in They can result from a number of set and has stopped heating the ground, different ways (figure 3). processes that cause the air closest heat radiates back into space, causing the Pho T o: BILL G o RD o N Under a surface temperature inversion air can separate into very stable layers (laminates) that can concentrate and transport airborne pesticides. Page 3 ground to cool. in turn, the air in contact 3. inversions created by smoke or dust hangs in the air and with the ground becomes cooler than the vegetation moves sideways, just above the air higher in the atmosphere. This generates surface; and vegetation and crops can shade the the surface temperature inversion. cumulus clouds that have built up during ground underneath them. The air in the day collapse towards evening. radiation inversions are the most contact with the ground will stay cooler dangerous for spraying operations as than adjacent areas where there is less other clues they cause airborne droplets to remain groundcover. This often occurs just concentrated at a low level for long periods. after sunrise. The air moving above the A surface temperature inversion is likely to Winds within the inversion can carry these vegetation or crop may be warmer than be present if: droplets long distances. the air below the vegetation. This can allow wind speed is constantly less than On gentle slopes, concentrated droplets airborne droplets to travel over, rather than 11km/h in the evening and overnight; can be transported many kilometres by through, vegetation. cool, off-slope breezes develop during drainage winds towards the lowest point in Transpiration from a dense crop canopy the evening or overnight; the catchment. under an inversion, where on a hot day can form a cool layer of air distant sounds become clearer and water runs from a property, droplets can just above the crop. Later in the day (when easier to hear; and move. See figure 3 (c). wind speeds tend to reduce) this layer of aromas become more distinct during cooler air can act like an inversion over the the evening than during the day. 2. inversions created by crop, making penetration of smaller spray advection (cool or warm air droplets into the canopy very difficult and clues that a surface movement) increasing the risk of off-target movement. temperature inversion is unlikely Cooler, denser air can move into an area and slide under layers of less dense, recognising a surface Applicators should always expect that a warm air. temperature inversion surface temperature inversion is most likely to have formed at sunset and will persist for This can happen when a cold front moves The scientific method for detecting a sometime after sunrise. However, a surface into an area, or a sea breeze pushes surface temperature inversion requires temperature inversion is unlikely if one or cooler air inland. it can also happen when the accurate measurement of the air more of the following has occurred: denser cool air moves down a slope temperature close to the ground and at and slides underneath layers of warm a height of at least 10m. On-farm, this continuous overcast weather, with low air in lower parts of the catchment. if is usually not practical, so most spray and heavy cloud; applicators must rely on visual clues. this occurs, the intensity of a radiation continuous rain; inversion increases. visual clues wind speed remains above 11km/h for Warm air can move over cool surfaces; the whole* time between sunset A surface temperature inversion is likely to some of the air closest to the ground and sunrise; and be present if: becomes cooler while the higher air stays after a clear night, cumulus clouds warmer. mist, fog, dew or a frost have occurred; begin to form. A A Droplets travel many kilometres close to the surface due to light breezes that lack turbulence, so the air is not mixed. Light winds B B Airborne pesticides and water vapour can move down gentle slopes and concentrate in lower parts of Drainage winds the catchment. C C Caught in complex thermals, droplets can move in Light winds unpredictable directions, particularly when the surface Base of eroding inversion temperature inversion begins to break down as the sun begins to heat the ground. At this time droplets can be lifted into higher layers of the inversion, where the Thermals Light winds wind movement could be in a different direction to that experienced closer to the ground. Legend Fine droplets, particles and vapour Medium droplets Coarse droplets FIGURE 3 Possible movement of airborne droplets in surface temperature inversion conditions. SOurCe GrAeme TePPer Page 4 *Sometimes the overnight wind speed Be aware of sensitive areas around the will provide efficacy. every nozzle can can pick up from virtually calm to speeds area to be sprayed. Sensitive areas produce small, driftable droplets. using greater than 11km/h during a surface include lower points in the catchment coarser spray qualities reduces the temperature inversion.
Load more

Recommended publications
  • The Art and Science of Forecasting Morning Temperature Inversions by Anthony J
    Air Quality Forecasting Excl usive Con tent The Art and Science of Forecasting Morning Temperature Inversions by Anthony J. Sadar Anthony J. Sadar is a Certified Consulting Meteorologist and Air Pollution Administrator with the Allegheny County Health Department, Air Quality Program in Pittsburgh, PA. E-mail: [email protected]. The author provides an overview of the key resources and variables used to produce morning surface air inversion forecasts in Pittsburgh, PA. Although the focus is southwestern Pennsylvania, the forecasting approach can be applied to similar locations across the globe. Air quality in southwestern Pennsylvania, as in most other areas of the Accurate forecasting of the onset of an inversion would benefit areas world, is very much influenced by surface-based temperature inver - prone to strong and/or persistent inversions. Advanced notice of im - sions. An atmospheric temperature inversion occurs when air temper - pending stagnant air conditions would give government regulators, ature increases with increasing height. In the layer of air nearest the industry operators, and the public time to mitigate emissions, and earth’s surface—the troposphere—this situation is the inverse of the hence, pollutant concentrations, as well as reduce exposure to “normal” condition where a warm ground keeps low-lying air warmer elevated pollution levels. than air higher up. Normally then, the warm surface air can rise and the cool air aloft can descend, causing the atmosphere to mix. Detecting Inversions To collect temperature, wind, and other data with height, the National A surface-based (or ground-level) temperature inversion forms Weather Service (NWS) releases a balloon-borne measurement trans - when air close to the ground cools faster than air at a higher altitude.
    [Show full text]
  • ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
    ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere.
    [Show full text]
  • Anticyclones
    Anticyclones Background Information for Teachers “High and Dry” A high pressure system, also known as an anticyclone, occurs when the weather is dominated by stable conditions. Under an anticyclone air is descending, maybe linked to the large scale pattern of ascent and descent associated with the Global Atmospheric Circulation, or because of a more localized pattern of ascent and descent. As shown in the diagram below, when air is sinking, more air is drawn in at the top of the troposphere to take its place and the sinking air diverges at the surface. The diverging air is slowed down by friction, but the air converging at the top isn’t – so the total amount of air in the area increases and the pressure rises. More for Teachers – Anticyclones Sinking air gets warmer as it sinks, the rate of evaporation increases and cloud formation is inhibited, so the weather is usually clear with only small amounts of cloud cover. In winter the clear, settled conditions and light winds associated with anticyclones can lead to frost. The clear skies allow heat to be lost from the surface of the Earth by radiation, allowing temperatures to fall steadily overnight, leading to air or ground frosts. In 2013, persistent High pressure led to cold temperatures which caused particular problems for hill sheep farmers, with sheep lambing into snow. In summer the clear settled conditions associated with anticyclones can bring long sunny days and warm temperatures. The weather is normally dry, although occasionally, localized patches of very hot ground temperatures can trigger thunderstorms. An anticyclone situated over the UK or near continent usually brings warm, fine weather.
    [Show full text]
  • Synoptic Meteorology
    Lecture Notes on Synoptic Meteorology For Integrated Meteorological Training Course By Dr. Prakash Khare Scientist E India Meteorological Department Meteorological Training Institute Pashan,Pune-8 186 IMTC SYLLABUS OF SYNOPTIC METEOROLOGY (FOR DIRECT RECRUITED S.A’S OF IMD) Theory (25 Periods) ❖ Scales of weather systems; Network of Observatories; Surface, upper air; special observations (satellite, radar, aircraft etc.); analysis of fields of meteorological elements on synoptic charts; Vertical time / cross sections and their analysis. ❖ Wind and pressure analysis: Isobars on level surface and contours on constant pressure surface. Isotherms, thickness field; examples of geostrophic, gradient and thermal winds: slope of pressure system, streamline and Isotachs analysis. ❖ Western disturbance and its structure and associated weather, Waves in mid-latitude westerlies. ❖ Thunderstorm and severe local storm, synoptic conditions favourable for thunderstorm, concepts of triggering mechanism, conditional instability; Norwesters, dust storm, hail storm. Squall, tornado, microburst/cloudburst, landslide. ❖ Indian summer monsoon; S.W. Monsoon onset: semi permanent systems, Active and break monsoon, Monsoon depressions: MTC; Offshore troughs/vortices. Influence of extra tropical troughs and typhoons in northwest Pacific; withdrawal of S.W. Monsoon, Northeast monsoon, ❖ Tropical Cyclone: Life cycle, vertical and horizontal structure of TC, Its movement and intensification. Weather associated with TC. Easterly wave and its structure and associated weather. ❖ Jet Streams – WMO definition of Jet stream, different jet streams around the globe, Jet streams and weather ❖ Meso-scale meteorology, sea and land breezes, mountain/valley winds, mountain wave. ❖ Short range weather forecasting (Elementary ideas only); persistence, climatology and steering methods, movement and development of synoptic scale systems; Analogue techniques- prediction of individual weather elements, visibility, surface and upper level winds, convective phenomena.
    [Show full text]
  • Thermal Inversion and Particulate Matter Concentration in Wrocław in Winter Season
    atmosphere Article Thermal Inversion and Particulate Matter Concentration in Wrocław in Winter Season Jadwiga Nidzgorska-Lencewicz * and Małgorzata Czarnecka Department of Environmental Management, West Pomeranian University of Technology in Szczecin, ul. Papie˙zaPawła VI, 71-459 Szczecin, Poland; [email protected] * Correspondence: [email protected] Received: 15 October 2020; Accepted: 7 December 2020; Published: 12 December 2020 Abstract: Studies on air quality frequently adopt clustering, in particular the k-means technique, owing to its simplicity, ease of implementation and efficiency. The aim of the present paper was the assessment of air quality in a winter season (December–February) in the conditions of temperature inversion using the k-means method, representing a non-hierarchical algorithm of cluster analysis. The air quality was assessed on the basis of the concentrations of particulate matter (PM10, PM2.5). The studies were conducted in four winter seasons (2015/16, 2016/17, 2017/18, 2019/20) in Wrocław (Poland). As a result of the application of the v-fold cross test, six clusters for each fraction of PM were identified. Even though the analysis covers only four winter seasons, the applied method has unequivocally revealed that the characteristics of surface-based (SBI) and elevated inversions (ELI) affect the concentration level of both fractions of particulate matter. In the case of PM10, the average lowest daily concentration (15.5 µg m 3) was recorded in the conditions of approx. 205 m in thickness, · − 0.5 ◦C intensity of the SBI and at the height of the base of the ELI at approx. 1700 m a.g.l., a thickness of 148 m and an intensity of 1.2 C.
    [Show full text]
  • Temperature Inversions.Pdf
    MID-ATLANTIC dronesKnowledge Elevated TEMPERATURE WHAT DOES IT MEAN FOR THE UAV PILOT? HOW DOES IT AFFECT THE WEATHER? INVERSION midatlanticdrones.com #TEMPERATUREINVERSION Temperature inversion: a layer of cool air at the surface is overlain by a layer of warmer air NORMAL CONDITIONS TEMPERATURE INVERSION COLD AIR COLD AIR COLD AIR COLD AIR WARMER AIR WARMER AIR COOLER AIR COOLER AIR WARMER AIR WARMER AIR COOLER AIR COOLER AIR On the left, arrows show normal conditions: Warm air rises and normal convective patterns persist. During temperature inversion, shown on the right, the warm air acts like a cap, shutting down convection and trapping smog over the city. #TEMPERATUREINVERSION warm air on top of cold air Expect fog and haze temp/dew point spread is low little convection – A temperature inversion means some warm air on top of some cold air. – The cold air underneath on the ground, along with a high relative humidity, means you are expecting fog in the cooler area. – If you check the METARS for the airports in the area as you will most likely have a temperature/dewpoint spread that is low. – The air will be smooth because there is little convection. #TEMPERATUREINVERSION 3 what does this mean for you, the drone pilot? Temperature inversions can represent an important element of air pollution, especially in places that are inhabitted, and in valleys. The warmer air layer acts as a natural lid that keeps pollution and dirt trapped. This trapped layer of dirty air stays in there unable to escape. The main issue for UAVs is visibility.
    [Show full text]
  • Glossary of Severe Weather Terms
    Glossary of Severe Weather Terms -A- Anvil The flat, spreading top of a cloud, often shaped like an anvil. Thunderstorm anvils may spread hundreds of miles downwind from the thunderstorm itself, and sometimes may spread upwind. Anvil Dome A large overshooting top or penetrating top. -B- Back-building Thunderstorm A thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain stationary or propagate in a backward direction. Back-sheared Anvil [Slang], a thunderstorm anvil which spreads upwind, against the flow aloft. A back-sheared anvil often implies a very strong updraft and a high severe weather potential. Beaver ('s) Tail [Slang], a particular type of inflow band with a relatively broad, flat appearance suggestive of a beaver's tail. It is attached to a supercell's general updraft and is oriented roughly parallel to the pseudo-warm front, i.e., usually east to west or southeast to northwest. As with any inflow band, cloud elements move toward the updraft, i.e., toward the west or northwest. Its size and shape change as the strength of the inflow changes. Spotters should note the distinction between a beaver tail and a tail cloud. A "true" tail cloud typically is attached to the wall cloud and has a cloud base at about the same level as the wall cloud itself. A beaver tail, on the other hand, is not attached to the wall cloud and has a cloud base at about the same height as the updraft base (which by definition is higher than the wall cloud).
    [Show full text]
  • Elevated Cold-Sector Severe Thunderstorms: a Preliminary Study
    ELEVATED COLD-SECTOR SEVERE THUNDERSTORMS: A PRELIMINARY STUDY Bradford N. Grant* National Weather Service National Severe Storms Forecast Center Kansas City, Missouri Abstract sector. However, these elevated storms can still produce a sig­ A preliminary study of atmospheric conditions in the vicinity nificant amount of severe weather and are more numerous than of severe thunderstorms that occurred in the cold sector, north one might expect. of east-west frontal boundaries, is presented. Upper-air sound­ Colman (1990) found that nearly all cool season (Nov-Feb) ings, suiface data and PCGRIDDS data were collected and thunderstorms east of the Rockies, with the exception of those analyzed from a total of eleven cases from April 1992 through over Florida, were of the elevated type. The environment that April 1994. The selection criteria necessitated that a report produced these thunderstorms displayed significantly different occur at least fifty statute miles north of a well-defined frontal thermodynamic characteristics from environments whose thun­ boundary. A brief climatology showed that the vast majority derstorms were rooted in the boundary layer. In addition, he of reports noted large hail (diameter: 1.00-1.75 in.) and that found a bimodal variation in the seasonal distribution of ele­ the first report of severe thunderstorms occurred on an average vated thunderstorms with a primary maximum in April and a of 150 miles north of the frontal boundary. Data from 22 secondary maximum in September. The location of the primary proximity soundings from these cases revealed a strong baro­ maximum of occurrence in April was over the lower Mississippi clinic environment with strong vertical wind shear and warm Valley.
    [Show full text]
  • PHAK Chapter 12 Weather Theory
    Chapter 12 Weather Theory Introduction Weather is an important factor that influences aircraft performance and flying safety. It is the state of the atmosphere at a given time and place with respect to variables, such as temperature (heat or cold), moisture (wetness or dryness), wind velocity (calm or storm), visibility (clearness or cloudiness), and barometric pressure (high or low). The term “weather” can also apply to adverse or destructive atmospheric conditions, such as high winds. This chapter explains basic weather theory and offers pilots background knowledge of weather principles. It is designed to help them gain a good understanding of how weather affects daily flying activities. Understanding the theories behind weather helps a pilot make sound weather decisions based on the reports and forecasts obtained from a Flight Service Station (FSS) weather specialist and other aviation weather services. Be it a local flight or a long cross-country flight, decisions based on weather can dramatically affect the safety of the flight. 12-1 Atmosphere The atmosphere is a blanket of air made up of a mixture of 1% gases that surrounds the Earth and reaches almost 350 miles from the surface of the Earth. This mixture is in constant motion. If the atmosphere were visible, it might look like 2211%% an ocean with swirls and eddies, rising and falling air, and Oxygen waves that travel for great distances. Life on Earth is supported by the atmosphere, solar energy, 77 and the planet’s magnetic fields. The atmosphere absorbs 88%% energy from the sun, recycles water and other chemicals, and Nitrogen works with the electrical and magnetic forces to provide a moderate climate.
    [Show full text]
  • Trade Wind Inversion
    Trade Wind Inversion Introduction The trade wind inversion is one of the most prominent manifestations of temperature inversions within the troposphere. Trade wind inversions are commonly found in association with the subtropical anticyclones connected to the descending branch of the time-averaged Hadley cell circulation. The trade wind inversion has impacts upon the sensible weather of the boundary layer across the subtropics and northern reaches of the tropics, particularly manifest in stability, cloud cover, and precipitation. In the following, we first describe the basic characteristics of the trade wind inversion and its impacts upon sensible weather in the tropics and subtropics. In so doing, we focus specifically upon its structure and impacts in the eastern North Pacific Ocean during Northern Hemisphere summer, although this can easily be generalized to any of the other ocean basins (e.g., eastern South Pacific Ocean, eastern North and South Atlantic Ocean, etc.) in which a trade wind inversion is present. We then develop lapse rate tendency equations to help us understand the factors influencing trade wind inversion formation and intensity. Key Concepts • What are the climatological structure and intensity of subtropical anticyclones? • How and why do vertical profiles of temperature and moisture vary with increasing distance from the center of a subtropical ridge? • What physical processes contribute to inversion formation and intensity? Trade Wind Inversion Structure and Impacts Trade wind inversions are commonly found in the eastern regions of the subtropical oceans and the western coastal regions of adjacent continents. The trade wind inversion is characterized by a layer in which temperature increases with increasing height above the surface layer, in which temperature decreases with increasing height.
    [Show full text]
  • Prmet Ch14 Thunderstorm Fundamentals
    Copyright © 2015 by Roland Stull. Practical Meteorology: An Algebra-based Survey of Atmospheric Science. 14 THUNDERSTORM FUNDAMENTALS Contents Thunderstorm Characteristics 481 Thunderstorm characteristics, formation, and Appearance 482 forecasting are covered in this chapter. The next Clouds Associated with Thunderstorms 482 chapter covers thunderstorm hazards including Cells & Evolution 484 hail, gust fronts, lightning, and tornadoes. Thunderstorm Types & Organization 486 Basic Storms 486 Mesoscale Convective Systems 488 Supercell Thunderstorms 492 INFO • Derecho 494 Thunderstorm Formation 496 ThundersTorm CharacterisTiCs Favorable Conditions 496 Key Altitudes 496 Thunderstorms are convective clouds INFO • Cap vs. Capping Inversion 497 with large vertical extent, often with tops near the High Humidity in the ABL 499 tropopause and bases near the top of the boundary INFO • Median, Quartiles, Percentiles 502 layer. Their official name is cumulonimbus (see Instability, CAPE & Updrafts 503 the Clouds Chapter), for which the abbreviation is Convective Available Potential Energy 503 Cb. On weather maps the symbol represents Updraft Velocity 508 thunderstorms, with a dot •, asterisk *, or triangle Wind Shear in the Environment 509 ∆ drawn just above the top of the symbol to indicate Hodograph Basics 510 rain, snow, or hail, respectively. For severe thunder- Using Hodographs 514 storms, the symbol is . Shear Across a Single Layer 514 Mean Wind Shear Vector 514 Total Shear Magnitude 515 Mean Environmental Wind (Normal Storm Mo- tion) 516 Supercell Storm Motion 518 Bulk Richardson Number 521 Triggering vs. Convective Inhibition 522 Convective Inhibition (CIN) 523 Triggers 525 Thunderstorm Forecasting 527 Outlooks, Watches & Warnings 528 INFO • A Tornado Watch (WW) 529 Stability Indices for Thunderstorms 530 Review 533 Homework Exercises 533 Broaden Knowledge & Comprehension 533 © Gene Rhoden / weatherpix.com Apply 534 Figure 14.1 Evaluate & Analyze 537 Air-mass thunderstorm.
    [Show full text]
  • Bibliography on Tropospheric Propagation of Radio Waves
    National Bureau of Standards Library, M.W. Bldg APR 8 1965 ^ecknical ^iote 304 BIBLIOGRAPHY ON TROPOSPHERIC PROPAGATION OF RADIO WAVES WILHELM NUPEN mm U. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS THE NATIONAL BUREAU OF STANDARDS The National Bureau of Standards is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. Its responsibilities include development and maintenance of the national stand- ards of measurement, and the provisions of means for making measurements consistent with those standards; determination of physical constants and properties of materials; development of methods for testing materials, mechanisms, and structures, and making such tests as may be necessary, particu- larly for government agencies; cooperation in the establishment of standard practices for incorpora- tion in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; assistance to industry, business, and consumers in the development and acceptance of commercial standards and simplified trade practice recommendations; administration of programs in cooperation with United States business groups and standards organizations for the development of international standards of practice; and maintenance of a clearinghouse for the collection and dissemination of scientific, tech- nical, and engineering information. The scope of the Bureau's activities is suggested in the following listing of its four Institutes and their organizational units. Institute for Basic Standards. Electricity. Metrology. Heat. Radiation Physics. Mechanics. Ap- plied Mathematics. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radio Stand- ards Laboratory: Radio Standards Physics; Radio Standards Engineering.** Office of Standard Ref- erence Data.
    [Show full text]