3. The Atmosphere

4. Today, human activity is altering the quantities of some of these variable gases CO2 CH4 N2O O3 CFCs

5. STRUCTURE AND SCIENCE OF THE ATMOSPHERE The atmosphere consists of four layers Troposphere –surface to 7 mi. Stratosphere 7-31 mi contains the ozone layer Mesosphere 31-51 mi Thermosphere up to 300mi

6. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Normally, temperature decreases as altitude increases in the troposphere, but sometimes a warm layer of air at mid-altitude will cover a layer of cold, dense air below, producing a thermal inversion This inversion layer traps emissions that then accumulate. This air quality factor is prevalent in many cities.

7. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Energy from the sun heats the planet’s surface unequally because of latitude differences and the tilt of the Earth’s axis This causes air and ocean circulation patterns that ultimately produce the seasons and influence weather and climate

8. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Weather specifies atmospheric conditions over short time periods and within relatively small geographical areas. Driven in part by the convective circulation of air being heated near Earth’s surface Air picks up moisture and rises Higher up it cools and condenses forming clouds Precipitation can result Cooler drier air descends beginning the cycle anew

9. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Climate describes the pattern of atmospheric conditions found across large geographic regions over long periods of time, typically seasons, years, or millennia

10. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Large-scale circulation systems consisting of pairs of convective cells produce global climate patterns Hadley convective cells near equator – intense solar radiation results in warm air rising and expanding and ultimately releasing the moisture that becomes the heavy rainfall of the tropics

11. STRUCTURE AND SCIENCE OF THE ATMOSPHERE Ferrel cells and polar cells are similar but less intense as the radiant energy decreases.