The Earth’s Atmosphere Contents Part 10 docx

Gas Law Equation of StateThe relationship among air pressure, air density, and air temperature can be expressed by Pressure = density × temperature × constant.. This relationship, often

1 square centimeter (cm2) = 0.15 in.2

1 square inch (in.2) = 6.45 cm2

1 square meter (m2) = 10.76 ft2

1 square foot (ft2) = 0.09 m2

Volume

1 cubic centimeter (cm3) = 0.06 in.3

1 cubic inch (in.3) = 16.39 cm3

Units, Conversions, Abbreviations, and Equations

= 0.02953 inch of mercury (in Hg)

= 0.01450 pound per square inch(lb/in.2)

*SI stands for Système International, which is the international

sys-tem of units and symbols.

TABLE A.2 SI Units* and Their Symbols

Quantity Name UnitsSymbol

Gas Law (Equation of State)

The relationship among air pressure, air density, and air

temperature can be expressed by

Pressure = density × temperature × constant

This relationship, often called the gas law (or equation

of state), can be expressed in symbolic form as:

p = ρRT

where p is air pressure, ρis air density, R is a constant,

and T is air temperature.

Stefan-Boltzmann Law

The Stefan-Boltzmann law is a law of radiation It states

that all objects with temperatures above absolute zero

emit radiation at a rate proportional to the fourth

power of their absolute temperature It is expressed

mathematically as:

E = σT4

where E is the maximum rate of radiation emitted each

second per unit surface area, T is the object’s surface

temperature, and σis a constant

Wien’s Law

Wien’s law (or Wien’s displacement law) relates an

object’s maximum emitted wavelength of radiation to

the object’s temperature It states that the wavelength of

maximum emitted radiation by an object is inversely

proportional to the object’s absolute temperature In

symbolic form, it is written as:

w

λmax =

T

where λmaxis the wavelength at which maximum

radia-tion emission occurs, T is the object’s temperature, and

w is a constant.

Geostrophic Wind Equation

The geostrophic wind equation gives an approximation

of the wind speed above the level of friction, where the

wind blows parallel to the isobars or contours The

equa-tion is expressed mathematically as:

V g =

2Ωsinφρ d

where Vgis the geostrophic wind, Ωis a constant (twice

the earth’s angular spin), sinφis a trigonometric

func-tion that takes into account the variafunc-tion of latitude (φ),

ρis the air density, ∆p is the pressure difference between

two places on the map some horizontal distance (d)

apart

Hydrostatic Equation

The hydrostatic equation relates to how quickly the air

pressure decreases in a column of air above the surface

The equation tells us that the rate at which the air

pres-sure decreases with height is equal to the air density

times the acceleration of gravity In symbolic form, it is

written as:

∆p

= –ρg

∆z

where ∆p is the decrease in pressure along a small

change in height ∆z, ρis the air density, and g is the

To determine e and e s , when the air temperature and

dew-point temperature are known, consult Table B.1

Simply read the value adjacent to the air temperature

and obtain e s; read the value adjacent to the dew-point

temperature and obtain e.

426 Appendix B

e = actual vapor pressure (millibars)

e s = saturation vapor pressure (millibars)

RH = relative humidity (percent)

Simplified Surface-Station Model

Pressure Tendency

Front Symbols

428 Appendix C

Miles (statute)

per hour Knots

1–23–89–1415–20

1–34–1314–1920–3233–4041–5051–6061–6970–7980–8788–9697–106107–114115–124125–134135–143144–198

Calm

Kilometers per Hour

Cold front (surface) Warm front (surface) Occluded front (surface) Stationary front (surface) Squall line

Trough (trof)

Wind Entries

To obtain the dew point (or relative humidity), simply

read down the temperature column and then over to

the wet-bulb depression For example, in Table D.1, a

temperature of 10°C with a wet-bulb depression of 3°C

429

produces a dew-point temperature of 4°C (Dew-pointtemperature and relative humidity readings are appro-priate for pressures near 1000 mb.)

TABLE D.1 Dew-Point Temperature (°C)

Wet-Bulb Depression (Dry-Bulb Temperature Minus Wet-Bulb Temperature) (°C)

TABLE D.2 Relative Humidity (Percent)

Wet-Bulb Depression (Dry-Bulb Temperature Minus Wet-Bulb Temperature) (°C)

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0

Wet-Bulb Depression (Dry-Bulb Temperature Minus Wet-Bulb Temperature) (°F)

Wet-Bulb Depression (Dry-Bulb Temperature Minus Wet-Bulb Temperature) (°F)

APPENDIX E

A Humid tropical All months have an average temperature of 18°C (64°F) or higher

f Tropical wet (rain forest) Wet all seasons; all months have at least 6 cm (2.4 in.) of rainfall

wTropical w et and dry Winter dry season; rainfall in driest month is less than 6 cm (2.4 in.) and

(savanna) less than 10 – P/25 (P is mean annual rainfall in cm)

m Tropical monsoon Short dry season; rainfall in driest month is less than 6 cm (2.4 in.) but equal to

or greater than 10 – P/25.

B Dry Potential evaporation and transpiration exceed precipitation The dry/humid

boundary is defined by the following formulas:

p = 2t + 28 when 70% or more of rain falls in warmer 6 months (dry winter)

p = 2t when 70% or more of rain falls in cooler 6 months (dry summer)

p = 2t + 14 when neither half year has 70% or more of rain (p is the mean annual precipitation in cm and t is the mean annual temperature in °C)*

S Semi-arid (steppe) The BS/BW boundary is exactly 1 ⁄2the dry/humid boundary

h Hot and dry Mean annual temperature is 18°C (64°F) or higher

k Cool and dry Mean annual temperature is below 18°C (64°F)

C Moist with mild winters Average temperature of coolest month is below 18°C (64°F) and above

–3°C (27°F) wDry w inters Average rainfall of w ettest summer month at least 10 times as much as in

driest winter month

s Dry summers Average rainfall of driest summer month less than 4 cm (1.6 in.); average rainfall

of wettest winter month at least 3 times as much as in driest summer month

f Wet all seasons Criteria for w and s cannot be met

a Summers long and hot Average temperature of warmest month above 22°C (72°F); at least 4 months

with average above 10°C (50°F)

b Summers long and cool Average temperature of all months below 22°C (72°F); at least 4 months with

average above 10°C (50°F)

c Summers short and cool Average temperature of all months below 22°C (72°F); 1 to 3 months with

average above 10°C (50°F)

D Moist with cold winters Average temperature of coldest month is –3°C (27°F) or below; average

temperature of warmest month is greater than 10°C (50°F)

a Summers long and hot Same as under C

b Summers long and cool Same as under C

c Summers short and cool Same as under C

d Summers short and cool; Average temperature of coldest month is –38°C (–36°F) or below

winters severe

E Polar climates Average temperature of warmest month is below 10°C (50°F)

T Tundra Average temperature of warmest month is greater than 0°C (32°F) but less

than 10°C (50°F)

F Ice cap Average temperature of warmest month is 0°C (32°F) or below

*The dry/humid boundary is defined in English units as: p = 0.44t –3 (dry winter); p = 0.44t –14 (dry summer); and p = 0.44t –8.6 (rainfall evenly distributed) Where p is mean annual rainfall in inches and t is mean annual temperature in °F.

Köppen’s Climatic Classification System

Letter Symbol Climatic

APPENDIX F

Heat Index (HI) Table

434

125 120 117 111 107 103 99 95 91 87 83 78 73 69 64

128 122 116 111 107 102 97 93 88 84 79 74 69 64

131 123 116 111 105 100 95 90 85 80 75 70 65

131 123 115 108 102 97 91 86 81 76 71 65

141 130 120 112 105 99 93 87 82 77 72 66

139 127 117 109 101 94 88 83 77 72 66

148 135 123 113 104 96 90 84 78 73 67

143 130 118 107 98 91 85 79 73 67

151 137 123 110 101 93 86 79 74 68

143 129 115 104 95 87 80 74 68

150 135 120 107 96 88 81 75 69

142 126 110 98 89 81 75 69

149 132 114 100 90 82 76 70

138 119 102 91 83 76 70

144 124 106 93 85 77 70

130 109 95 86 77 70

136 113 97 86 78 71

117 99 87 78 71

122 102 88 79 71

105 89 79 71

108 91 80 72

APPENDIX G

Beaufort Wind Scale (Over Land)

wind vanes

2 Slight breeze 4–7 4–6 7–11 Wind felt on face; leaves rustle; wind vanes moved by

wind; flags stir

3 Gentle breeze 8–12 7–10 12–19 Leaves and small twigs move; wind will extend light flag

4 Moderate breeze 13–18 11–16 20–29 Wind raises dust and loose paper; small branches move;

flags flap

5 Fresh breeze 19–24 17–21 30–39 Small trees with leaves begin to sway; flags ripple

6 Strong breeze 25–31 22–27 40–50 Large tree branches in motion; whistling heard in

telegraph wires; umbrellas used with difficulty

7 High wind 32–38 28–33 51–61 Whole trees in motion; inconvenience felt walking

against wind; flags extend

9 Strong gale 47–54 41–47 75–87 Slight structural damage occurs (signs and antennas

blown down)

10 Whole gale 55–63 48–55 88–101 Trees uprooted; considerable damage occurs

TABLE G.1 Estimating Wind Speed from Surface Observation

Number Description mi/hr knots km/hr Observations

CHAPTER 1

Fig 1.1 NASA photo.

Fig 1.2 Photo by author.

Fig 1.4 © David Weintraub/Photo Researchers

Fig 1.10 NOAA photo.

Fig 1.12 Photo by author.

Fig 1.13 © Luc Vidal/Ponopresse/Gamma Liaison.

Fig 1.14 © Warren Faidley/Weatherstock.

Fig 1.15 AP/Wide World.

Fig 1.16 © Keith Kent/Science Photo

Library/Photo Researchers.

Fig 1 Photo by author.

CHAPTER 2

Figs 2.3, 2.12, 2.23 Photos by author.

Fig 2.18 © Michael Orton, Tony Stone Images.

Fig 2.20 © Robert Mackinlay/Peter Arnold.

Fig 2 Johnny Johnson, Allstock.

CHAPTER 3

Figs 3.5 and 3.6 Photos by author.

Fig 3.7 Courtesy of the Modesto Bee,

photography by Ted Benson.

Figs 3.12 and 3.13 Data from U.S Department of

4.31, and 4.33 Photos by author.

Fig 4.12 Photo by Ross DePaola.

Fig 4.15 © Russell D Curtis/Photo Researchers.

Fig 4.28 Courtesy of T Ansel Toney

Fig 4.30 Photo by Dick Hilton.

Figs 4.34 and 4.35 Photos by Pakka Parviainen.

CHAPTER 5

Fig 5.4 Photo by J L Medeiros.

Fig 5.6, 5.10, 5.11, 5.24, and 5.29 Photos by

author.

Fig 5.14 Photo by Peter Wiinikka.

Fig 5.23 Photo by Ross DePaola.

Fig 5.25 © Scott Cunazine/Photo Researchers.

Fig 5.27 National Center for Atmospheric

Research/University Corporation for Atmospheric

Research/National Science Foundation.

Fig 5.28 NOAA photo.

Fig 5.30 National Center for Atmospheric

Research/University Corporation for Atmospheric

Research/National Science Foundation.

Fig 5.34 Weather Graphics Courtesy of

AccuWeather, Inc 385 Science Park Road, State

College, PA 16803 (814)237-0309 © 1999

CHAPTER 6

Figs 6.24 and 6.27 Photos by author.

Fig 5 © Richard R Hansen/Photo Researchers.

CHAPTER 7

Fig 2 National Center for Atmospheric

Research/University Corporation for Atmospheric Research/National Science Foundation.

Fig 7.5 Photo courtesy T Ansel Toney.

Figs 7.8 and 7.10 Photos by author.

Fig 7.13 Courtesy of Sherwood B Idso.

Fig 7.27 Courtesy of NOAA.

CHAPTER 8

Fig 8.4 NOAA photo.

Fig 8.8 NOAA photo.

CHAPTER 9

Fig 9.1 Courtesy of NOAA/NWS.

Fig 9.2 Photo courtesy Jan Null.

Fig 9.3 Figure courtesy J T Johnson, National

Severe Storms Laboratory, Norman, OK.

Figs 9.8a, 9.8b, 9.9, 9.10, and 9.11 NOAA Photos.

Figs 9.13 Data taken from “Statistical Probabilities

for a White Christmas,” U.S Department of Commerce.

Fig 2 and Fig 3 Photos by author.

CHAPTER 10

Figs 10.2, 10.4, 10.9, and 10.24 Photos by author.

Fig 10.3 Photo © Howard B Bluestein.

Fig 10.7 Photo by Ron Smith.

Fig 10.10 Doppler radar, National Weather Service.

Figs 10.13 and 10.16 NOAA photos.

Fig 10.17 Wide World Photos.

Fig 10.18 After Thunderstorms, Vol 2, U.S

Govern-ment Printing Office, Washington, D.C., 1982.

Fig 10.19 Data courtesy of NOAA.

Fig 10.22 Photo © Richard Lee Kaylin.

Fig 10.25 Global Atmospherics, Inc.

Fig 2 Photo by Johnny Autery.

Fig 10.26 Photo by Mary K Hurley.

Fig 10.27 Data courtesy of NOAA.

Fig 10.30 Photo © Wade Balzer, Weatherstock.

Fig 10.33 Photo © Howard B Bluestein.

Fig 10.34 National Center for Atmospheric

Research.

Fig 10.35 National Center for Atmospheric

Research/University Corporation for Atmospheric Research/National Science Foundation.

Photographer: Jim Wilson.

Figs 10.36 National Severe Storms Laboratory and

the NEXRAD Operational Support Facility, courtesy Andy White.

Fig 10.37 Photo © Howard B Bluestein.

Fig 10.38 Photo © G Kaufman.

CHAPTER 11

Fig 11.2 NASA photo.

Fig 11.4 Image courtesy of Intellicast.com © 1998

WSI Corporation Reprinted with permission.

Fig 11.5 Photo © Comstock.

Figs 11.7, 11.10, 11.13, 11.14, AND 11.15

NOAA/National Weather Service.

Fig 11.16 Photo © Weather Catalog/Media

Fig 12.1 NASA photo.

Fig 12.2a and 12.2b Courtesy John Day and the

University of Colorado Health Sciences Center.

Fig 12.4 Photo by author.

Figs 1 and 2 NASA photos.

Fig 12.12 Photo by J L Medeiros.

Fig 12.13 Photo by Jim Edwards, Riverside Press

CHAPTER 14

Fig 14.1 Photos by author.

Fig 14.2 Modified from CLIMAP, 1976 Fig 14.4 Modified from Understanding Climate

Change, National Academy of Sciences, 1975.

Fig 14.5 Modified from Robert T Watson, et al.,

Climate Change 1995: Impacts, Adaptations and Mitigation of Climate Change, Cambridge

University Press, Cambridge, England, 1996.

Fig.14.10 From J M Barnola, et al., “Vostok ice

core provides 160,000-year record of atmospheric

CO2, Nature (1 Oct., 1987), 329: 460.

Fig 14.11 Gamma Liaison.

Fig 14.12 Data courtesy of John Christy,

University of Alabama, Huntsville, and R Spencer, NASA Marshall Space Flight Center.

Fig 14.13 From V Ramanathan, B R Barstrom,

and E F Harrison, “Climate and the earth’s radiation budget,” Physics Today (May, 1989), Fig 5,

p 27.

Fig 14.14 © Frans Lanting, Minden Pictures Fig 14.15 After F B Mitchell, et al., “Transient cli-

mate response to increasing sulphate aerosols and

greenhouse gases.” Nature (1995) 376: 501–504.

Fig 1 © Chris Butler/SPL/Photo Researchers.

CHAPTER 15

Figs 15.4, 15.5, 15.8, 15.12, 15.14, 15.19, 15.22, 15.27, 15.29, and Fig 4 Photos by author Fig 15.13 Photo by Pakka Parviainen.

Fig 15.17 Courtesy of T Ansel Toney Fig 15.20 Science Source/Photo Researchers Fig 1 Photo by Pakka Parviainen.

Fig 15.23 NOAA photo.

Fig 15.30 Photo by Elizabeth Beaver Burnett Fig 15.31 Photo by Pakka Parviainen.

Fig 2 Photo by H Michael Mogil.

Absolute humidity The mass of water vapor in a given

vol-ume of air It represents the density of water vapor in the air

Absolute zero A temperature reading of –273°C, –460°F,

or 0K Theoretically, there is no molecular motion at this

temperature

Absolutely stable atmosphere An atmospheric condition

that exists when the environmental lapse rate is less than the

moist adiabatic rate This results in a lifted parcel of air being

colder than the air around it

Absolutely unstable atmosphere An atmospheric

condi-tion that exists when the environmental lapse rate is greater

than the dry adiabatic rate This results in a lifted parcel of air

being warmer than the air around it

Accretion The growth of a precipitation particle by the

col-lision of an ice crystal or snowflake with a supercooled liquid

droplet that freezes upon impact

Acid deposition The depositing of acidic particles (usually

sulfuric acid and nitric acid) at the earth’s surface Acid

depo-sition occurs in dry form (dry depodepo-sition) or wet form (wet

de-position) Acid rain and acid precipitation often denote wet

deposition (See Acid rain.)

Acid fog See Acid rain.

Acid rain Cloud droplets or raindrops combining with

gaseous pollutants, such as oxides of sulfur and nitrogen, to

make falling rain (or snow) acidic—pH less than 5.0 If fog

droplets combine with such pollutants it becomes acid fog.

Actual Vapor Pressure See Vapor pressure.

Adiabatic process A process that takes place without a

transfer of heat between the system (such as an air parcel) and

its surroundings In an adiabatic process, compression always

results in warming, and expansion results in cooling

Advection The horizontal transfer of any atmospheric

property by the wind

Advection fog Occurs when warm, moist air moves over a

cold surface and the air cools to below its dew point

Advection-radiation fog Fog that forms as relatively warm

moist air moves over a colder surface that cooled mainly by diational cooling

ra-Aerosols Tiny suspended solid particles (dust, smoke, etc.)

or liquid droplets that enter the atmosphere from either ural or human (anthropogenic) sources, such as the burning

nat-of fossil fuels Sulfur-containing fossil fuels, such as coal,

pro-duce sulfate aerosols.

Aerovane A wind instrument that indicates or records both

wind speed and wind direction Also called a skyvane.

Aggregation The clustering together of ice crystals to formsnowflakes

Air density See Density.

Air mass A large body of air that has similar horizontal

tem-perature and moisture characteristics

Air-mass thunderstorm See Ordinary thunderstorm.

Air-mass weather A persistent type of weather that may last

for several days (up to a week or more) It occurs when an areacomes under the influence of a particular air mass

Air parcel See Parcel of air.

Air pollutants Solid, liquid, or gaseous airborne substancesthat occur in concentrations high enough to threaten the health

of people and animals, to harm vegetation and structures, or totoxify a given environment

Air pressure (atmospheric pressure) The pressure exerted

by the mass of air above a given point, usually expressed inmillibars (mb), inches of mercury (Hg) or in hectopascals(hPa)

Albedo The percent of radiation returning from a surfacecompared to that which strikes it

Aleutian low The subpolar low-pressure area that is tered near the Aleutian Islands on charts that show mean sea-level pressure

cen-Altimeter An instrument that indicates the altitude of

an object above a fixed level Pressure altimeters use ananeroid barometer with a scale graduated in altitude instead

of pressure

439

Glossary