ATMOSPHERE

Composition of the Atmosphere The atmosphere is comprised of a variety of gases: Major Constituents (99%): Nitrogen (N): 78% Oxygen (O2): 21% Trace Constituents: Other: 1%

Recycling of Atmospheric Materials

Movement of Heat Energy Radiation: the transfer of energy through space in the form electromagnetic waves. Convection: the transfer of heat energy in a liquid or gas through the motion caused by differences in density. Conduction: the transfer of heat energy through collisions of the atoms or molecules of a substance.

Heat and Temperature Temperature: is a measure of the average kinetic energy of atoms or molecules in the substance. Heat: the total kinetic energy of all of the particles of the substance.

Troposphere: The lowest region of the atmosphere (0 to 15 km altitude) Where weather occurs It contains 99% of the water vapor and 75% of the atmospheric gases Temperature decreases with altitude. Top of the troposphere is known as the tropopause

Stratosphere 15 to 50 km altitude Heating occurs because ozone (O3) absorbs ultraviolet radiation from the Sun. Temperature increases with altitude due to ozone absorbing ultraviolet radiation. Top of the stratosphere is known as the stratopause

Mesosphere 50 to 90 km altitude Temperature decreases with altitude The lowest temperatures in the entire atmosphere are found in this layer Top of the mesosphere is known as the mesopause

Thermosphere 90 to 500 km altitude Temperature increases with altitude above 90 km, and is constant above 200 km. heating is due to absorption of solar radiation. The highest temperatures in the atmosphere found in this layer

Ionosphere: Occurs within the mesosphere and thermosphere between 90 and 500 km. Layer of electrically charged particles Effected by solar events Auroras (Northern and Southern lights).

Exosphere: The exosphere is the outer most layer of the atmosphere. The temperature in the exosphere goes up with altitude. Satellites orbit Earth in the exosphere

Insolation and the Atmosphere Insolation: incoming solar radiation. some solar radiation is absorbed by gases in the atmosphere some solar radiation reaches the Earth’s surface some solar radiation is scattered in the atmosphere and is returned to space

Heat Budget of Earth and the Atmosphere 50% of solar radiation reaches the Earth’s surface Small % of insolation is absorbed by the atmosphere Energy is transferred by radiation conduction evaporation condensation of water energy transfer is the major cause of Earth’s weather

Heat Budget of Earth and the Atmosphere carbon dioxide and water vapor absorbs most of the infrared radiation prevents energy from radiating back into space creating the Greenhouse effect. Without the Greenhouse Effect, Most of the heat energy would be lost to space Earth’s average temperature would be about 33oC cooler. increased levels of carbon dioxide (CO2) in the atmosphere Could cause the Earth’s heat budget be out of balance Causes Global Warming.

Temperature variations due to Insolation intensity of insolation varies due to: time of day latitude time of year. Color affects how much insolation is absorbed and how the absorbed energy affects the temperature

Intensity of Insolation Intensity of insolation is depended on the angle at which the sun’s rays strike Earth’s surface. the sun at 90o, Earth receives the maximum amount of energy. Occurs at noon, Earth’s surface heats up quickly As the angle of insolation decreases the amount of energy received decreases Warmest temperatures occur several hours after noon, lower atmosphere receives more energy from the ground than it loses Coolest temperatures occur right before dawn, ground and atmosphere have lost most of its heat

Intensity of Insolation intensity of insolation is affected by the latitude. closer to the equator the sun’s rays are almost vertical, climate is hotter Moving either north or south of the equator the angle of insolation decreases, the energy spreads out over a larger area, climate is colder

Intensity of Insolation At mid-latitudes sun ray’s nearly vertical in the summer; summers are hot. winter the angle of insolation is at its lowest; winters are cold. Northern Hemisphere greatest angle of insolation occurs around Jun 21, thus July is the warmest month of the year. lowest angle of insolation occurs around December 21, thus January is the coldest month. The southern hemisphere is the reverse

The affect of the insolation on sea-level temperatures in January and July. What changes do you notice?

Human Impact on the Atmosphere

Acid Rain Forms due to pollutants Acidity is measured by pH. sulfur dioxide and nitrogen dioxide react with water vapor Acidity is measured by pH. The lower the pH the more acidic the rain.

Smog Temperature inversion: when the temperature at the Earth’s surface is cooler than the air above it, convection does not occur

Ozone Depletion Hole in Ozone layer due to pollution of chloroflurocarbons (CFCs). Greatly reduced due to the elimination of CFCs. Thin Ozone/Hole forms each spring over Antarctica. Thinning Ozone/hole allows for exposure to ultraviolent radiation which is dangerous to living things.