Climate and Climate Change Unit 2: The Atmosphere

Weather v. Climate Weather is the stage of the atmosphere at a particular place at a particular point in time Climate is the long-term prevailing weather conditions at a particular place based upon data gathered Example: Phoenix v. Seattle

Climate-determining Factors Latitude Atmospheric circulation patterns Oceanic circulation patterns Local geography, solar, and volcanic activity

Latitude Distance measured from the equator North or South (in degrees) Amount of solar energy received is dependent on latitude Where is it greater? Seasonality High latitudes – sunlight hits the earth at an oblique angle Hours of daylight vary greatly What is equator? Poles?

Climate-determining Factors Latitude Atmospheric circulation patterns Oceanic circulation patterns Local geography, solar, and volcanic activity

Atmospheric Circulation Patterns Three important properties of air: Cold air sinks (why?); compresses and warms Warm air rises (expands and cools) Warm air can hold more water vapor (so what happens when it cools?) Wind – movement of air within an atmosphere At the equator, cool air cannot sink because warm air is pushing it up. Pushes cool air towards about 30 degrees N/S! Poles are also very dry As the air sinks, it becomes warmer creating very dry conditions (warm air causes evaporation at the surface)

Prevailing Winds Winds that blow predominantly in one direction Because of the Coriolis effect (the earth is rotating), these winds do not blow directly north or south To the right in the N Hemisphere, to the left in the southern hemisphere

Climate-determining Factors Latitude Atmospheric circulation patterns Oceanic circulation patterns Local geography, solar, and volcanic activity

Oceanic Circulation Patterns Why do oceans have a great effect on climate (think PoWater)? Movement of surface ocean currents is by winds and rotation of the Earth El Nino – Southern Oscillation – periodic change in location of warm and cold water mases Winds in the Western Pacific (near China) strengthen and push warm water East (towards the US) Increase in rain in the U.S., and drought in Indonesia/Australia Number of El Nino years are increasing! La Nina is the opposite

Climate-determining Factors Latitude Atmospheric circulation patterns Oceanic circulation patterns Local geography, solar, and volcanic activity

Local Geography, Solar/Volcanic Activity Temperatures fall about 6 degrees Celsius for every 1000m increase in elevation! Precipitation is affected too! (Rain Shadow) Solar maximum – sun emits an increased amount of UV radiation Volcanic eruptions – release what? Reacts with water vapor and dust which forms a haze cooling the temperature

Seasonal Changes in Climate What causes seasons? Angles at which the rays strike the earth changes as the earth moves around the sun Why do our hemispheres have flipped seasons