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Chapter 4


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Weather - is the combination of temperature, humidity, precipitation, wind, cloudiness, and other atmospheric conditions at a specific place and time.

Climate - is the long-term average pattern of weather. Description of local, regional and global.


4.1 Earth intercepts solar radiation

Outer edge of atmosphere

Thermal patterns

Earth’s rotation/movement around sun

prevailing winds and ocean currents

influences distribution of rainfall

Energy budget

Travels through space as waves


sun = 6000 o C

short-wave radiation

Earth surface = 15 o C ( cooler )

long wave radiation


Greenhouse effect

Inbound radiation

from sun passes through atmosphere with ease

Ozone layer O 3

Outbound radiation

long wavelength from Earth cannot escape easily

Send CO 2 + water vapor back to Earth


4.2 Intercepted solar radiation varies over Earth’s surface

Amount of solar energy intercepted


higher radiation at a greater angle

spreads over larger area

radiation intercepts atmosphere at an angle travels through deeper layer

meet more particles, more returns to space

Explains difference of temperature in tropics and at the poles

fig. 4.3 page 32


Equinox and Solstice

Earth tilted 23 degrees from vertical with respect to the sun.

seasonal differences



Northern Hemisphere

summer solstice

Tropic of Cancer

Southern Hemisphere

winter solstice

Tropic of Capricorn

Arctic and Antarctic Circles

Mean annual temperature


4.3 Air temperature decreases with altitude

Air gets cooler with altitude

Mt. Kilimanjaro - ice and snow capped

Physical properties of air molecules

adiabatic cooling


adiabatic lapse rate


4.4 Air masses circulate globally

fig. 4.4 page 33

Warm air rises

Cool air more dense

fig. 4.7 page 35

Coriolis force

G. C. Coriolis - French mathematician

fig. 4.8


Series of belts of prevailing winds


horse latitudes


northeast tradewinds



4.5 Solar energy, wind, and Earth’s rotation create ocean currents

Currents - systematic patterns of water movement

Gyres - oceans dominated by two great circular water motions

Northern Hemisphere - clockwise

Southern Hemisphere - counterclockwise

fig. 4.10


4.6 Temperature influences the amount of moisture air can hold

saturation vapor pressure -

relative humidity -

dew point -


4.7 Precipitation has a global pattern

Gathering of moisture

High precipitation in tropic regions

Asia, South America, Africa, SE North America

fig. 4.12 page 38


4.8 Most organisms live in microclimates


page 39 " Urban Microclimates "

Rain shadow

page 40 - 42

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