Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Atmosphere

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings I. Atmosphere Basics A.Atmosphere = the thin layer of gases that surrounds Earth B. Atmosphere Basics 1) Absorbs radiation and moderates climate 2) Transports and recycles water and nutrients 3) 78% nitrogen gas, 21% oxygen gas, 1% other gases 4) Five layers that differ in temperature, density and composition

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings I. Atmosphere Basics C. Very small concentrations of permanent (remain at stable concentrations) and variable gases (varying concentrations) D. Permanent gases include neon, helium, hydrogen and xenon E. Variable gases include water vapor, carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), ozone (O 3 ) and chlororfluorocarbons (CFCs) F. Human activity is changing the amounts of variable gases in the atmosphere.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The atmosphere’s composition

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings II. Layers of the Atmosphere A. Starting from earth and working out into space, the layers of the atmosphere are the troposphere, stratosphere, mesophere, thermosphere, and exosphere

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings II. Layers of the Atmosphere B. Troposphere = bottommost layer 1) Air for breathing, weather 2. The densest layer – contains the highest concentrations of all atmospheric gasses. 3) Temperature declines with altitude 4) Tropopause = limits mixing between troposphere and the layer above it

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings II. Layers of the Atmosphere C. Stratosphere = km (7-31 mi) above sea level 1) Drier and less dense, with little vertical mixing 2) Colder in its lower regions 3) Contains UV radiation-blocking ozone, km (10-19 mi) above sea level

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings II. Layers of the Atmosphere D. Mesosphere = km (31-56 mi) above sea level -Extremely low air pressure -Temperatures decrease with altitude E. Thermosphere = atmosphere’s second to the top layer X-rays from the sun - “Northern lights” formed when sun’s energy hits charged gas molecules in this layer -Extends upward to 500 m (300 mi)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings II. Layers of the Atmosphere F. Exosphere – Outermost layer - Extremely low in density

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The atmosphere’s four layers

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings III. Atmospheric properties A. Atmospheric pressure = measures the force per unit area produced by a column of air -Decreases with altitude B. Relative humidity = the ratio of water vapor a given volume of air contains to the amount it could contain at a given temperature C. Temperature = varies with location and time

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings III. Atmospheric properties D. The spatial relationship between the Earth and sun determines the amount of solar energy striking the Earth E. Energy from the sun 1) Heats air 2) Moves air 3) Creates seasons 4) Influences weather and climate F. Solar radiation is highest near the equator

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings III. Atmospheric properties G. Pressure and density of air in the atmosphere leads to weather systems 1) High-pressure system = air that moves away from a center of high pressure as it descends -Brings fair weather 2) Low-pressure system = air moves toward the low atmospheric pressure at the center of the system and spirals upward -Clouds and precipitation

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings III. Atmospheric properties H. Air Masses Produce Weather 1) Front = the boundary between air masses that differ in temperature, moisture, and density. Usually produces precipitation or storms. 2) Warm Front = the boundary where warm moist air replaces colder, drier air 3) Cold Front = the boundary where colder, drier air displaces warmer, moister air

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings III. Atmospheric properties I. Usually, tropospheric air temperature decreases as altitude increases -Warm air rises, causing vertical mixing J. Thermal inversion = a layer of cool air occurs beneath a layer of warmer air K. Denser, cooler air at the bottom of the layer resists mixing, trapping pollutants in the troposphere

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

IV. The Greenhouse Effect A.As Earth’s surface absorbs solar radiation, it increases in temperature and emits infrared radiation (heat). B.When this infrared radiation bounces back to space, it interacts with the gases in the atmosphere (causes the molecules to vibrate), which in turn reflects a lower-energy infrared radiation (heat) back to the lower atmosphere and earth.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

C. The greenhouse effect is the ability of our atmosphere to trap heat and release some of this heat energy back to the lower atmosphere and earth. D. The natural greenhouse effect is critical to life on earth – without it temperatures would be over 60 F cooler on earth.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings E. Thinking another way… 1.Without the greenhouse effect: Sun’s radiation → absorbed by Earth → Re-radiated to space as heat 2. With the greenhouse effect: Sun’s Radiation → absorbed by Earth → some re-radiated to space as heat heat → some trapped by the atmosphere

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings F. As we increase the concentrations of heat-trapping greenhouse gases in the atmosphere, more heat from the sun is kept in the earth’s lower atmosphere, the crust, and the oceans. G. The percentage of incoming sunlight that is reflected from a surface is called its albedo. The higher the albedo of a surface, the more solar energy it reflects, and the less it absorbs.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings H. A white surface has a higher albedo than a black surface, so it tends to stay cooler. I. Earth has an average albedo of 30%, but tropical regions with dense forests have albedo values of 10-20%, and snow covered polar regions have albedo values of %.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings V. El Nino A.El Nino Southern Oscillation (ENSO) is a systematic shift in atmospheric pressure, sea surface temperature, and ocean circulation in the tropical Pacific Ocean. B.El Nino conditions are triggered when air pressure increases in the western Pacific and decreases in the eastern Pacific, causing the equatorial winds to weaken.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings IV. El Nino C. The normal build up of warm water in the western Pacific is reversed, which stops the normal cold-water upwelling in the Eastern Pacific. Not only is this a problem for the marine life that depend on the nutrient- rich cold water, but it dramatically shifts normal precipitation patterns around the world.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings IV. El Nino D. ENSO cycles are periodic but irregular, occurring every 2 to 8 years.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings V. El Nino Video 1)Why is the fishing so good in Peru and Ecuador? 2)What is El Nino? 3)Besides causing fishing problems, name three other problems caused by El Nino.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings V. El Nino Video 4) Why is the western Pacific 10 C warmer than water at the same latitude in the Eastern Pacific? 5) What happens every 4 to 7 years? 6) What are some of the specific damages that happened in the 1982 El Nino? 7) What did Ethiopia do to prepare for ENSO?