Factors That Affect ClimateCHAPTER 22.1

Climate vs. Weather….

Climate: An established pattern of weather over a long period of time

Weather: the day to day variations of the condition of the atmosphere

Determining Climate

CLIMATES are determined through data collected on temperature & precipitation averaged ANNUALLY, MONTHLY, & DAILY

The ranges (difference between avg. low & high) for temp. & precip. levels are also used

To be reliable at determining a climate, scientists must look at extremes, averages, & ranges!

What influences the temperatures & precipitation?Latitude

Heat absorption & releaseTopography

Latitude…Solar Energy: The higher the latitude, the

less energy is absorbed by the sunThe tilt of the Earth’s axis is also important

(seasons)Belts of air at different densities result from

this unequal heating of the Earth!

Latitude Cont…

Global Wind Patterns: cool, dense air at poles----warm, light air at equator

Cool air is high pressure/Warm air is low pressure (These differences create WIND)

Wind Belts (Based on lines of latitude) Doldrums (0o-30o) : near equator, air rises-cools-expands, large

amounts of precipitation Subtropical Highs (30o-60o): air sinks, warms, lowers humidity,

little precipitation (deserts) Subpolar Lows (50o-70o): frequent cyclones and other severe

storms (helps to form polar front)

Heat Absorption & Balance…

Different areas absorb/release heat differently. (land faster than water)

So, the air temps over these areas affects the climate.

Specific heat and evaporation----Water has high specific heat (heat required to raise 1 gram of water 1 oC)

Ocean Currents---winds blow toward shore, then these sea breezes can affect land climate.

El Nino-Southern Oscillation (ENSO)—cycle of changing wind and water current patterns in the Pacific Ocean.

Every 3-10 years El Nino causes surface water temps along coast of South America to rise—this causes an increase in severe storms in the Pacific.

Seasonal Winds (monsoons): Temp differences between land and ocean causes wind to shift seasonally. Winter—land to ocean Summer—ocean to land

Heat Absorption & Balance…

El Nino has a cool water phase--La Nina (increases amount of Atlantic Hurricanes).

Topography…

Surface features (mountains, valleys) also influence climate.

Elevation (high elevation—low temps) Rain Shadows (air mass moisture lost as

precipitation as it “climbs” upslope on a mountain) ---other side of mountain experiences dry, warm air. This dry wind that goes “downslope” is called a foehn in

the Alps, a chinook in the Rockies.