Characteristics of the Atmosphere

Composition of Atmosphere Made up mostly of Nitrogen (N) Oxygen makes up a little more than 20%

Atmospheric Pressure Gravity pulls molecules towards Earth Creates air pressure Atmosphere is held by gravity As altitude increases, air pressure decreases

Atmospheric Layers -sphere: ball; each layer surrounds Earth like a hollow ball -tropo: turning or change; gases turn and mix - strato: layer; gases are layered - meso: middle - thermo: heat; temps are highest here

Layers of the Atmosphere Troposphere Stratosphere Mesosphere The layer in which we live Lies next to Earth’s surface Weather occurs here As altitude increases, temp decreases Home of the Ozone layer As altitude increases, temp increases Middle layer Coldest layer

Layers of the Atmosphere cont’d Edge of the Atmosphere Uppermost layer As altitude increases, temp increases also 1,000˚C, but doesn’t feel hot! Not it’s own layer, but located in the Upper Mesosphere and Lower Thermosphere Contains electrically charged particles called ions Home of the Auroras Nitrogen and Oxygen absorb harmful solar energy Thermosphere Ionosphere

Check Up Write each question and answer (in complete sentences) in your notes. List the layers of the atmosphere, starting with the one closest to Earth. Why does air pressure decrease as altitude increases? How can the thermosphere have high temperatures but not feel hot? What two gases make up most of the atmosphere? Explain how density affects the transfer of thermal energy in the air. If you finish early, get an Earth science book and begin reading the section assigned for homework.

Global Winds and Local Winds

Why Air Moves Equator and Poles Cold air sinks Creates a high pressure around the poles Cold air then flows toward the equator

Pressure Belts Coriolis Effect Every 30° latitude Bands of high and low pressure Curving of path of currents due to Earth’s rotation

Global Winds Polar Easterlies Westerlies Wind belts that extend from the poles to 60° latitude Wind belts found between 30° and 60° latitude

Trade Winds Doldrums Winds that blow from 30° to almost the equator Where trade winds meet around the equator

Horse Latitudes Jet Streams At about 30° North and 30° South Sinking air creates an area of high pressure Narrow belts of high- speed winds Blow in the upper Troposphere and lower Stratosphere

Local Winds Generally move short distances Can blow from any direction Mountain and Valley Breezes Sea and Land Breezes Generally move short distances Can blow from any direction Caused by an area’s geography Affected by temperature Local Winds

Sea Breeze Land Breeze wind that blows from an ocean or lake to land land warms faster than water happens during day winds that blow from land to a body of water land cools faster than water happens at night

Air Pollution

Primary Pollutants Secondary Pollutants Pollutants put directly into the air by human or natural activity When primary pollutants react with other primary pollutants or natural substances (water vapor)

Industrial Air Pollution Indoor Air Pollution Burning of fossil fuels Ex: Power plants Sometimes can be more polluted than outside air

Ozone Ozone Hole Layer is thinning over the Arctic and Antarctic regions Allows more UV radiation to reach Earth’s surface CFCs cause Ozone depletion CFCs remain active for 60-120 years

Human Effects from Air Pollution Short-term effects Long-term effects Coughing Sneezing Headaches Eye irritation Lung cancer

Clean Air Act EPA Requires many industries to use pollution-control devices Sets air quality standards