复旦大学：《能源与环境 Energy and the Environment》教学课件_9_Air Pollution & Global Effects

Contents: 1. Energy Fundamentals, Energy Use in an Industrial Society Click to LOOK INSIDE 2. The Fossil Fuels, Heat Engines Roxs A Rising/ art /. kraushaar 3. Heat Engines 4. Renewable Energy Sources 5. Nuclear Energy 6. Energy Conservation 7。 Air pollution ENERGY Global effects ENVIRONMENT Text Book Energy and the Environment(2nd Edition) by Robert A. Ristinen Jack J Kraushaar

Contents: 1. Energy Fundamentals, Energy Use in an Industrial Society 2. The Fossil Fuels, Heat Engines 3. Heat Engines 4. Renewable Energy Sources 5. Nuclear Energy 6. Energy Conservation 7. Air Pollution 8. Global Effects Text Book : Energy and the Environment (2nd Edition) by Robert A. Ristinen & Jack J. Kraushaar

Air pollution

Air Pollution

1. Spaceship earth It's only in recent decades that there has been widespread awareness that our atmosphere and oceans can no longer be considered as infinite The rate of dumping wastes has increased with increasing population and the expanding technical base for our way of life There is now clear evidence that we are seriously polluting the one atmosphere that we have The sources of atmospheric pollution are many and have far-reaching results The solution to pollution is dilution!

1. Spaceship Earth It’s only in recent decades that there has been widespread awareness that our atmosphere and oceans can no longer be considered as infinite. The rate of dumping wastes has increased with increasing population and the expanding technical base for our way of life. There is now clear evidence that we are seriously polluting the one atmosphere that we have. The sources of atmospheric pollution are many and have far-reaching results. The solution to pollution is dilution!

2. The Earths Atmosphere Some numbers. Weight: 5.7x1015 tons, one-millionth the weight of the earth Area: 200 million square miles Thickness: hundreds of miles Half of the air is below 18.000 feet altitude above see level Density at sea level: 1.3 kg/m3 Pressure at sea level: 14.7 lb/in2(1.01x105 N/m2) The density and the corresponding pressure, gradually decrease with altitude By 50,000 feet the pressure has been reduced to 1.6 Ib/in,, and by 600 miles altitude the atmospheric pressure is essentially zero

2. The Earth’s Atmosphere Some numbers: • Weight: 5.7x1015 tons, one-millionth the weight of the earth. • Area: 200 million square miles. • Thickness: hundreds of miles. Half of the air is below 18,000 feet altitude above see level. • Density at sea level: 1.3 kg/m3 . • Pressure at sea level: 14.7 lb/in2 (1.01x105 N/m2 ) The density and the corresponding pressure, gradually decrease with altitude. By 50,000 feet the pressure has been reduced to 1.6 lb/in2 , and by 600 miles altitude the atmospheric pressure is essentially zero

-93-73-53 13-3717% Thermosphere) 350-800 km Mesopause 250 mesosphere) 80-85 km 2 E0 Stratopause Stratosphere 50-55km affects us most directly and with Tro which we are mainly Troposphere concerned 160180200220240260280300 extends to 7 km at Temperature( K) the poles and 17 km at the equator. Ff igure 9.1 The temperature of the atmosphere as a · In the greek word ction of altitude the arrows indicate the normal trope, meaning turn of temperature variation and the dots the extreme values or overturn The names given to the various regions of the atmosphere are shown on the right

Figure 9.1 The temperature of the atmosphere as a function of altitude. The arrows indicate the normal range of temperature variation and the dots the extreme values. The names given to the various regions of the atmosphere are shown on the right. • affects us most directly and with which we are mainly concerned. • extends to 7 km at the poles and 17 km at the equator. • In the Greek word trope, meaning turn or overturn. 350–800 km 80–85 km 50 - 55 km

Table 9.1 Major Permanent Constituents of the Atmosphere Ga as Percent by volume parts per Million Nitrogen(N 7808 Oxygen(O2) Argon(Ar) 0.93 Neon(Ne) 18.2 Helium(He) 5.2 Krypton(Kr) ydrogen(H2) 0.5 In addition to these permanent gases, there are a number of others, such as water vapor, carbon dioxide, methane, carbon monoxide, ozone and ammonia, that fluctuate with time altitude and location Water vapor: <1%-3%

Table 9.1 Major Permanent Constituents of the Atmosphere. In addition to these permanent gases, there are a number of others, such as water vapor, carbon dioxide, methane, carbon monoxide, ozone and ammonia, that fluctuate with time, altitude, and location. Water vapor: < 1% - 3%

3. Thermal Inversions What is the purpose of the tall smokestacks we see at coal-burning power plants? 93-73-53-33-13-3717 Normally a negative temperature gradient exists near the earth Id this has important 250 70 consequence for the dispersal of pollutants 200 A parcel of warm polluted air released into the lower levels of 40 the atmosphere under normal meteorological conditions, it will 100 rise in the atmosphere to as much as 10.000 meters 50 However, not all meteorological 10 conditions are conducive to this 160180200220240260280300 upward motion of the warmed polluted

3. Thermal Inversions • Normally a negative temperature gradient exists near the earth, and this has important consequence for the dispersal of pollutants. • A parcel of warm polluted air released into the lower levels of the atmosphere under normal meteorological conditions, it will rise in the atmosphere to as much as 10,000 meters. • However, not all meteorological conditions are conducive to this upward motion of the warmed polluted air. What is the purpose of the tall smokestacks we see at coal-burning power plants?

The generally prevalent temperature-altitude relationship in the lower atmosphere is known as the adiabatic lapse rate(ALR,绝热递降速率 adiabatic: no heat energy is either gained or lost by some defined volume of gas lapse: temperature decreases with increasing altitude If a given parcel of air, warmer than its surroundings, starts to rise in the atmosphere, and if it can be considered to do without exchanging heat energy with the neighboring air, it will expand and cool at the adiabatic lapse rate An approximate average ALR is-0.65 oC/100m or-3 oF/1000feet The alR, in simple terms is the rate at which the temperature of a volume of air will naturally tend to decrease as altitude increase, or increase as altitude decreases

The generally prevalent temperature-altitude relationship in the lower atmosphere is known as the adiabatic lapse rate (ALR, 绝热递降速率). adiabatic: no heat energy is either gained or lost by some defined volume of gas lapse: temperature decreases with increasing altitude If a given parcel of air, warmer than its surroundings, starts to rise in the atmosphere, and if it can be considered to do without exchanging heat energy with the neighboring air, it will expand and cool at the adiabatic lapse rate. An approximate average ALR is -0.65 oC/100m or -3 oF/1000feet. The ALR, in simple terms, is the rate at which the temperature of a volume of air will naturally tend to decrease as altitude increase, or increase as altitude decreases

Scenario 1 If the atmospheric temperature decreases more rapidly with altitude than ALR because of unusual meteorological circumstances, then any parcel of air released near ground level and warmer than its surroundings will rise indefinitely into the upper atmosphere This is because as it cools at the alr, it will always be warmer and thereby less dense, than the surrounding air This unstable condition is obviously desirable because it leads to good vertical mixing and a relatively pollution-free lower atmosphere

Scenario 1 If the atmospheric temperature decreases more rapidly with altitude than ALR because of unusual meteorological circumstances, then any parcel of air released near ground level and warmer than its surroundings will rise indefinitely into the upper atmosphere. This is because as it cools at the ALR, it will always be warmer, and thereby less dense, than the surrounding air. This unstable condition is obviously desirable because it leads to good vertical mixing and a relatively pollution-free lower atmosphere

Scenario 2 If the atmospheric temperature decreases more slowly with altitude than indicated by the ALR, a volume of warm air released near ground level will rise in the ambient cooler air, cooling at the alr as it rise, until at some level it is no longer warmer than its surroundings at which point it will then cease to rise Scenario 3 If the existing temperature profile and the alr happen to be the same there will be a neutral condition that neither forces the warm air upward nor traps it near the earth

Scenario 2 If the atmospheric temperature decreases more slowly with altitude than indicated by the ALR, a volume of warm air released near ground level will rise in the ambient cooler air, cooling at the ALR as it rise, until at some level it is no longer warmer than its surroundings, at which point it will then cease to rise. Scenario 3 If the existing temperature profile and the ALR happen to be the same, there will be a neutral condition that neither forces the warm air upward nor traps it near the earth