C LIMATE Chapter 21

F ACTORS THAT A FFECT C LIMATE Latitude Less solar energy as you move away from the equator Tropical zones Rays from the sun hit close to a right angle 23.5 degrees north (Tropic of Cancer) 23.5 degrees south (Tropic of Capricorn) Temperate zones 23.5 degrees to 66.5 degrees North and South Light hits at a smaller angle so it spreads out more (less intense) More sunlight each day in the summer and less in the winter Polar zones 66.5 degrees to the poles Light hits at an even smaller angle so it spreads out even more (less intense)

F ACTORS THAT A FFECT C LIMATE Elevation Height above sea level Temperature decreases as elevation increases A drop of 6.5 degrees Celsius for every 1000 meters More precipitation occurs as clouds increase in elevation Topography Rain falls on the windward side of mountains leaving the leewards side dry Bodies of Water Large bodies of water as warmth and moisture to the air

Atmospheric Circulation Global Wind move warmth and moisture From the equator towards the poles Vegetation Transpiration is how plants release water into the atmosphere so the more plants the more moisture The amount and type of vegetation changes how much heat is absorbed and released Plants may also release particles that become nuclei for condensation and precipitation What kind of plant grows is based on light availability, temperature, and moisture (climate) A climate is often named based on the vegetation F ACTORS THAT A FFECT C LIMATE

W ORLD C LIMATE Koppen Climate Classification System Uses mean monthly and annual values of temperature and precipitation to classify climates Humid tropical climates Dry climates Humid mid-latitude climates Polar climates Highland climates

H UMID T ROPICAL C LIMATES No winters Precipitation of more than 200 centimeters Mean temperature of 18 degree Celsius Wet Tropical Climates Tropical rain forests Tropical Wet and Dry Climates There are dry periods even though total annual rainfall can come close to a rainforest Savannahs

H UMID M ID -L ATITUDE C LIMATES Mild winters Coldest month average temperature ranges between 18 degrees Celsius and -3 degrees Celsius Humid subtropical 25 to 40 degrees latitude Eastern side of continents Hot humid summers with mild winters Marine West Coast 40 to 55 degrees latitude Mild winters and cool summers with plenty of precipitation Dry Summer Subtropical 30 to 45 degrees latitude Plenty of winter precipitation

H UMID M ID -L ATITUDE C LIMATES Severe Winters Coldest month has an average temperature below -3 degrees Celsius Humid Continental 40 to 50 degrees latitude Warm summers and severe winters More precipitation in the summer than the winter Subarctic North of the humid continental and south of the tundras Long very cold winters but summers are short and warm

D RY C LIMATES Annual precipitation is less than the potential loss of water due to evaporation Remember evaporation is related to temperature As air descends it can hold more water so precipitation doesn’t happen often Arid (Desert) Semi-arid (Steppe) Usually found on the edges of deserts Rain Shadow Deserts Leeward side of high mountains

O THER C LIMATES Polar Climates Mean temperature is the warmest month is below 10 degrees Celcius Perpetual night in winter Summer days are long but cool Tundras are cold deserts Ice Cap climates has no month above zero Celcius Highland Climates Localized in regions with high altitude Generally cooler and wetter than low lying regions but precipitation can vary based on the side of the mountain

C LIMATE C HANGES Natural Process that change climates Volcanic Eruptions Put ash and dust into the atmosphere Includes sulfur which can cause acid rain Also increases carbon dioxide in atmosphere Can block sunlight and lower temperature Ocean Circulation El Nino results in more rain because the ocean is warmer

C LIMATE CHANGE Natural Processes continued… Solar Activity Sunspots occur when the sun is most active – corresponds to warm periods on Earth Earth Motions As the plates move the position of land relative to water changes The shape of our orbit has changed bring us closer to and further from the sun Our tilt has also changed (the smaller the tilt the less difference between summer and winter)

C LIMATE C HANGE Human Impacts Greenhouse Effect Warming of Earth’s lower atmosphere and surface Water vapor and carbon dioxide Absorb solar radiation The more of these gases in our atmosphere the more radiation that gets absorbed Burning of fossil fuels releases carbon dioxide Clearing of forests means fewer plants to removed carbon dioxide

C LIMATE C HANGE Global Warming Global temperatures have increased This means there will be more evaporation (more water vapor in the air which makes global warming worse) Glaciers are melting so the sea level is rising and there will be more flooding Sea ice is melting which means more solar radiation will be absorbed by the ocean Hurricanes will get more intense Heat waves and droughts will become more common