Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.of the weight of all the air above. B.90% of Earth’s atmosphere is in the troposphere. C.of warmer temperatures. D.of water vapor. Atmospheric pressure is greatest near the Earth’s surface because Solar Radiation CHECK YOUR NEIGHBOR

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.of the weight of all the air above. B.90% of Earth’s atmosphere is in the troposphere. C.of warmer temperatures. D.of water vapor. Atmospheric pressure is greatest near the Earth’s surface because Solar Radiation CHECK YOUR ANSWER

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.is a pollutant that creates smog. B.depleted from the stratosphere contributes to an increase of harmful UV rays at Earth’s surface. C.is detrimental to life on Earth. D.at the troposphere contributes to skin cancer. The “ozone hole” is considered to be a problem, because ozone Solar Radiation CHECK YOUR NEIGHBOR

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.is a pollutant that creates smog. B.depleted from the stratosphere contributes to an increase of harmful UV rays at Earth’s surface. C.is detrimental to life on Earth. D.at the troposphere contributes to skin cancer. The “ozone hole” is considered to be a problem, because ozone Solar Radiation CHECK YOUR ANSWER

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Climate Zones The world is divided into different climate zones. Temperatures are: Highest in the tropics, near the equator Lower nearer the poles Moderate and variable in the temperate zone

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Temperature Depends on Latitude Why does the temperature depend on latitude? Latitude affects temperature because the Sun’s rays strike different latitudes at different angles.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Temperature Depends on Latitude When the Sun’s rays strike a surface at right angles, the rays strike the smallest possible area. They are the most concentrated at this angle and have maximum solar intensity. Solar intensity – solar radiation per area.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Temperature Depends on Latitude Which climate zone would have the highest solar intensity? Tropical

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Temperature Depends on Latitude Which climate zone would have the lowest solar intensity? Polar

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Temperature Depends on Latitude Temperate climate zones have a moderate solar intensity. Tropical TemperatePolar

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Days and Years Earth’s revolution (orbit) around the Sun determines the length of a year (365 days). Earth’s rotation on its axis determines day length—24 hours in each day. The number of daylight hours varies during the year depending on latitude.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Why Are There Seasons? When the Sun’s rays are closest to perpendicular at any spot on the Earth, that region’s season is summer. Six months later, as the rays fall upon the same region more obliquely, the season is winter. In between are the seasons fall and spring.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Variation in solar intensity with latitude and the tilt of the Earth’s axis helps to explain the different seasons. Why Are There Seasons? The combination of more direct rays and longer days creates the warmth of summer.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Why are There Seasons? At the summer solstice (June 21st),locations north of the Arctic Circle in the Northern Hemisphere have ~24 hours of daylight. At the winter solstice (December 22nd), locations north of the Arctic Circle have ~24 hours of night. In the Southern Hemisphere, the Antarctic Circle, the seasons are reversed (summer solstice is in December).

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A.winter; spring B.summer; fall C.summer; winter D.winter; summer On the fourth of July in Kansas City, Missouri, the season is _________. On the fourth of July in Perth, Australia, the season is ___________. CHECK YOUR NEIGHBOR

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.winter; spring B.summer; fall C.summer; winter D.winter; summer On the fourth of July in Kansas City, Missouri, the season is _________. On the fourth of July in Perth, Australia, the season is ___________. CHECK YOUR ANSWER

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Flow of the Atmosphere - Wind If you puncture a tire or a balloon, you can hear and feel the air escaping. Why does the air rush out of the balloon and tires? Air moves naturally from a region of high pressure to a region of low pressure. Wind is air that flows horizontally from higher pressure to lower pressure. Larger differences in air pressure produce stronger, faster winds.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Flow of the Atmosphere - Wind

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley What Causes Differences in Air Pressure? Warm air characteristics: Warm air expands Warm air has lower density and lower pressure Pressure differences are caused by uneven heating of the Earth’s surface. Cool air characteristics: Cool air contracts Cool air has higher density and higher pressure

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Local Winds Which way to does the sea breeze blow and why? Animation of Sea Breeze Not all surfaces are heated equally. Example: Land heats and cools more rapidly than water. Unequal heating results in pressure differences. And pressure differences result in wind. Remember: Wind is air that flows horizontally from higher pressure to lower pressure.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Global Winds Global Winds: Planet-scale differences occur because of solar intensity variations—equatorial regions have greater solar intensity than polar regions. —Differences contribute to global wind patterns—prevailing winds.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley The Coriolis Effect Earth’s rotation greatly affects the path of moving air. Coriolis effect: moving bodies (such as air) deflect to the right in the Northern Hemisphere, to the left in the Southern Hemisphere. Deflection of wind varies according to speed and latitude. —Faster wind, greater deflection —Deflection greatest at poles, decreases to zero at equator

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A.to the right in the Northern Hemisphere and left in the Southern Hemisphere. B.to the left in the Northern Hemisphere and right in the Southern Hemisphere. C.laterally toward the poles. D.westward. The prevailing westerly winds are affected by the Coriolis effect by the deflection of winds CHECK YOUR NEIGHBOR

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A.to the right in the Northern Hemisphere and left in the Southern Hemisphere. B.to the left in the Northern Hemisphere and right in the Southern Hemisphere. C.laterally toward the poles. D.westward. The prevailing westerly winds are affected by the Coriolis effect by the deflection of winds CHECK YOUR ANSWER Explanation: Winds are named for the direction from which they blow. Westerlies blow from the west to the east.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Circulation of the Atmosphere Summary Factors that affect wind: The pressure gradient force: air moves from high pressure to low pressure The Coriolis effect: apparent deflection of winds due to Earth’s rotation Frictional force: air moving close to ground encounters friction —Surface friction reduces wind speed, which reduces the effect of Coriolis.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oceanic Circulation: Currents Ocean currents are streams of water that move, relative to the larger ocean. Surface currents are created by wind. –Surface ocean currents correspond to the directions of the prevailing winds.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oceanic Circulation: Currents Factors that influence ocean currents: For short distances, wind is strongest factor For longer distances, Coriolis effect comes into play: —Coriolis causes surface currents to turn and twist into semicircular whirls called gyres. —Northern Hemisphere gyres rotate clockwise. —Southern Hemisphere gyres rotate counterclockwise.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oceanic Circulation: Currents Surface currents redistribute Earth’s heat. The Gulf Stream current carries vast quantities of warm tropical water into higher latitudes. –Great Britain and Norway have warmer winter temperatures (for their latitude) because of the Gulf Stream.

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Water in the Atmosphere Water vapor is water in the gaseous phase. Water vapor in the atmosphere produces humidity, clouds, and precipitation.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Humidity Humidity is the mass of water vapor a given volume of air contains. There is always some water vapor in the air.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Humidity Air that contains as much water vapor as it possibly can is saturated. –Warm air holds more water vapor than cold air. –As air cools, it holds less and less water vapor. Saturation can occur when air temperature drops, causing water vapor to condense. Saturation and condensation are more likely in cold air—slower-moving molecules.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Humidity Dew point is the temperature at which saturation occurs. Condensation occurs when the dew point is reached. –Water vapor condenses high in the atmosphere and forms clouds. –Water vapor condenses close to the ground surface to form dew, frost, and/or fog.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Clouds Cloud - visible aggregate of minute water droplets or tiny ice crystals. How do clouds form? –Clouds form as moist, warm air rises, then cools to its dew point and water vapor condenses. Solid particles must be present for the water molecules to condense on.

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Precipitation Precipitation – water in the liquid or solid phase that returns to Earth’s surface from the atmosphere. Rain, snow, sleet, hail, and mist.

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