Environmental Science Chapter 7 Notes #1

Atmosphere Thin Layer of gases that surrounds the Earth Extends from the surface to 100’s of km’s above “Air” –Composition 78% Nitrogen 21% Oxygen 1% = water vapor, argon, carbon dioxide, neon, helium, and others –2 most important Oxygen for respiration Carbon Dioxide for photosynthesis

Atmosphere Living organisms appeared about 4 billion years ago –Changed out the atmosphere Depleted the oxygen –Plant evolved to photosynthesize –Allowed for increased oxygen in the atmosphere Photosynthesis and Respiration keep oxygen and carbon dioxide constant

Atmosphere Our atmosphere has 5 layers –The layers get less dense the further you move out from Earth’s surface 1. Troposphere –Nearest to Earth’s Surface –Extends out to 10 km (6 mi) –Where most weather occurs –Contains 90% of the atmosphere’s gases

Atmosphere 2.Stratosphere 1.10 km to 50 km (about 30 mi) 2.Less dense than troposphere 3.Contains the ozone layer 1.Protects us from UV rays 4.Wind blows – not as much turbulence as in troposphere 3.Mesosphere 1.50 km to 80 km (about 50 mi) 2.Less dense than the troposphere and the stratosphere

Atmosphere 4.Thermosphere 1.80 km to 500 km (310 mi) 2.Less dense than all three of the above 5.Exosphere 1.Beyond the thermosphere 2.Gases become thinner and thinner 3.It eventually just merges with outer space

Climate Weather –What is happening in the atmosphere at a particular place at a particular time Climate –Average weather in an area over a long period of time –Aspects of climate Temperature Humidity Wind Precipitation Temp and precip. Generally determines what type of organisms are able to live in a particular region

What Determines Climate? 1.Latitude 1.Distance from the equator 2.Measured in degrees N or S 3.Solar energy received depends on latitude 2.Air Circulation 1.Cold air sinks and warms as it does so 2.Warm are rises and cools as it does so 3.Warm air holds more water than cold air 4.As warm air rises it causes wind (mvmt of air) 5.End result – areas of heavy precipitation, dry areas, etc.

What Determines Climate? 3. Ocean Currents 1.Currents redistribute large masses of hot and cold water 2.Mvmt cause by winds and rotation of the Earth 3.Oceans make climates more moderate (warm winters and cool summers) 4.Local Geography 1.Height above sea level affects temp 2.Mountains influence the distribution of precipitation

Seasonal Change in Climate Result in Earth’s orbit around the sun In the Northern Hemisphere the Earth tilts so that we get more direct sunlight in the summer than in the winter We are closest to the sun in the winter! Equator gets direct sunlight year around – so its always warm (tropics)

Seasonal Change in Climate