Chapter 17 Atmosphere • Page 365 • What does the photograph show? • How does the quality of the air in the photograph compare to that of your community today? • How might the photograph be different if it was taken on the following day? • What makes up the atmosphere? • How do human activities affect the atmosphere?
The atmosphere in Balance • The early atmosphere of the earth was primarily created through volcanic eruptions. • Consisted mostly of CO2, SO2, H2O, and Nitrogen • Oxygen was thought to have been created in the upper atmosphere by the destruction of water molecules through Photosynthesis • Today’s atmosphere (99%) is mostly nitrogen and oxygen
Recycling of Atmospheric materials • Composition of the atmosphere changes very little because it is an efficient recycling system • P. 367 Picture explains the O2, CO2, and H2O cycles
A Delicate Balance • The atmosphere may become unbalance by both natural and human origins • e.g. CO2 levels in Hawaii have rose 16% between 1959 and 1999
Environmental Consultant Median annual earnings of environmental scientists were $51,080 in May 2004. The middle 50 percent earned between $39,100 and $67,360. The lowest 10 percent earned less than $31,610, and the highest 10 percent earned more than $85,940. Median annual earnings of hydrologists were $61,510 in May 2004, with the middle 50 percent earning between $47,080 and $77,910, the lowest 10 percent earning less than $38,580, and the highest 10 percent earning more than $94,460. Median annual earnings in the industries employing the largest number of environmental scientists in May 2004 were as follows: Federal Government$73,530Management, scientific, and technical consulting services51,190Architectural, engineering, and related services49,160Local government48,870State government 46,850
Chapter 17.2 • Page 696 • Convert 70°F Celsius • When is the Fahrenheit Scale used? • The Celsius Scale? • Which do you prefer?
Heat and the Atmosphere • Energy from the sun drives the atmosphere
How Heat Moves • Radiation – transfer of energy through space in the form of visible light • does not require a medium – pass through a vacuum • Conduction – transfer of heat energy by touch • e.g. air bough warm ground becomes warmer • Convection – Transfer of heat energy in a liquid or gas caused by differences in density • e.g. warm air heated by the surface of earth becomes less dense and rises
Heat and Temperature • Temperature – is the measure of the average K.E. of the atoms in the substance • Heat is the total KE of all the particles in a substance • e.g. A tablespoon of water at 100 Celsius has less heat than a cup of water at 100 Celsius • Thermometer is used to measure temperature • At sea level water freezes at 0 Celsius and Boils at 100° Celsius
Structure of the Atmosphere • is divided into 4 layers based on temperature p. 371
Troposphere – lowest layer of the atmosphere where all weather occurs • Temperature decreases with height
Stratosphere – clear dry layer above the Troposphere • Contains the Ozone(O3) Which absorbs UV radiation • Temperature increases with increased height
Mesosphere - the 3rd layer • Temperature decreases with height
Thermosphere – 4th layer • very thin and separated by layers of different gasses • due to the intense solar radiation temperature increases with height • contain the ionosphere • Auroras are formed when electrically charged particles are attracted to the earth’s poles
Insulation and the Atmosphere • Incoming solar radiation is called insulation • Earth receives only two-billionths of the suns rays • Of 100 units (p. 373) of suns energy 30 reflected back into space, 19 Absorbed by the atmosphere, 51 absorbed by Earth’s surface • Unequal insulation caused temperature differences
Discussion – Global Heat Budget • Page 373 • Explain why most of the atmosphere’s heat energy comes indirectly from the sun.
Chapter 17.3 • Which surface is likely to be hotter on a sunny day: • A parking lot blacktop • One with crushed white gravel
Local Temperature Variations • Caused by insulation (energy) heats Earth’s surface and atmosphere unequally
Intensity of Insulation • The angle at which the suns rays strike the earth, the more overhead (90) the more energy • Time of day - Suns rays are closest to vertical at noon. However, the highest temperature occur later in the day because of time needed for the surface to create heat using the insulation • Latitude and equator 90 more insulation where as high latitude sun rays strike at more of an angle less insulation
Time of year – mid latitude locations have higher temperatures in summer because the rays are more direct than in winter • Year’s maximum insulation occurs in June but max temperate are in July, weakest sunlight in December but lowest temps are in January • Cloud Cover – more insulation on clear days because clouds reflect sunlight. However, they hold the heat in at night.
Heating of Water and Land • Water and land warm up and cool off at different rates. Water warms more slowly than land and cools more slowly. • Suns energy penetrates water deeper spreading it out • Some energy is used in evaporation • Water has a higher specific heat • Different hard surfaces absorb radiation differently • light colored surfaces absorbs less than dark • e.g. blacktop gets warmer than grass
Temperature Maps (p. 377) • Land heats and cools off faster than water therefore continents are warmer than nearby oceans in summer and cooler than nearby oceans in winter • Isotherm lines on a map connect places of equal temperatures
Common Air Pollutants • Air Pollution – any airborne gas or particle that occurs at a concentration capable of harming humans or the environment • Clean air act 1970 Identifies 6 key pollutants – CO, NO2, SO2 Pb, O3 and particulates
Acid Rain – Forms when sulfur dioxide and nitrogen oxides react with water vapor in the air. Then falls out with rain and snow • Life forms are sensitive to pH • pH scale 0-14 each increase is 10x the prior • Increased Acid has killed off lakes in Canada and in upper New York • Can also damage limestone structures
Smog - Photochemical Smog - brown haze that forms in air pollution with nitrogen oxides and hydro carbons that come mainly from cars • Creates ground level zones – irritant to lungs and stunts plant growth and yields • Temperature inversion – air at surface is colder than the air above trapping pollutants close to the ground
Ozone Depletion • Thought to be caused by Chlorofluorocarbons. CFC’S are used in aerosols, air conditioners, and solvents that are banned in the U.S. • Ozone absorbs UV form the sun that cause skin cancer in humans
Global Warming • Green house gases such as CO2 trap heat at the earth’s surface • Gasses could be increased form the burning of fossil fuels and global deforestation. • Possible effects • Rising seal levels • Increasing frequency and severity of storms • More frequent heat waves and droughts • Relocation of major crop-growing areas