Factors That Affect Climate CHAPTER 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 temperature & precipitation  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 & release  Topography

Latitude…  Solar Energy: The higher the latitude, the less energy is absorbed by the sun  The 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 (0 o -30 o ) : near equator, air rises-cools-expands, large amounts of precipitation  Subtropical Highs (30 o -60 o ): air sinks, warms, lowers humidity, little precipitation (deserts)  Subpolar Lows (50 o -70 o ): 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 o C)  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.