1 Global Changes in the Atmosphere Climate, Global Warming and Ozone Depletion msnbcmedia.msn.com/j/msnbc/Components/Photos/...

2 What Causes Climate? “Weather” is the condition of the atmosphere at a certain place and time “Weather” is the condition of the atmosphere at a certain place and time Climate is the average year-after- year conditions of temperature, precipitation, winds, and clouds in an area Climate is the average year-after- year conditions of temperature, precipitation, winds, and clouds in an area Two main factors determine climate: temperature, precipitation Two main factors determine climate: temperature, precipitation

3 Global Warming Over the last 120 years, the average temperature of the troposphere has risen by 0.5° Celsius Over the last 120 years, the average temperature of the troposphere has risen by 0.5° Celsius Global Warming is the gradual increase in the temperature of Earth’s atmosphere Global Warming is the gradual increase in the temperature of Earth’s atmosphere The Greenhouse Effect is a natural process by which heat is trapped in the atmosphere by water vapor, carbon dioxide, methane and other gases that form a “blanket” around the Earth. The Greenhouse Effect is a natural process by which heat is trapped in the atmosphere by water vapor, carbon dioxide, methane and other gases that form a “blanket” around the Earth.

4 Melting Glaciers/ Ice Caps

5 Melting Glaciers/ Ice Caps

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7 Factors Affecting Temperature Main factors that influence temperature –L–L–L–Latitude –A–A–A–Altitude –d–d–d–distance from large bodies of water –o–o–o–ocean currents. Latitude is the distance from the equator, measured in degrees. Climates of areas farther from the equator tend to be cooler than areas close to the equator.

8 Temperature Zones Tropical zone: From the equator, to 23.5° North and South, climates are warm. Frequent direct sunlight Tropical zone: From the equator, to 23.5° North and South, climates are warm. Frequent direct sunlight Polar zones: Near poles, from 66.5° to 90° North and from 66.5° to 90° South, climates are cold Polar zones: Near poles, from 66.5° to 90° North and from 66.5° to 90° South, climates are cold Temperate zones: From tropical zone to polar zones (23.5°-66.5°North and South). Climates in these areas vary from having warm or hot summers to having cool or cold winters Temperate zones: From tropical zone to polar zones (23.5°-66.5°North and South). Climates in these areas vary from having warm or hot summers to having cool or cold winters

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10 Prevailing Winds Winds that blow mainly from one direction. Winds that blow mainly from one direction. These winds influence an area’s moisture and temperature. These winds influence an area’s moisture and temperature. These affect the amount of precipitation an area receives These affect the amount of precipitation an area receives –From moist, wet area – rain –From dry, cool areas – very little rain

11 Prevailing Winds and Precipitation A mountain range in the path of prevailing winds can influence where precipitation falls A mountain range in the path of prevailing winds can influence where precipitation falls * When humid winds blow from the ocean toward a mountain range the air is forced to rise up the mountains. The warm humid air cools and condenses this forms clouds and maybe rain or snow

12 Windward and Leeward Rain or snow tends to fall on the windward side of the mountain, the side that the wind hits first Rain or snow tends to fall on the windward side of the mountain, the side that the wind hits first The leeward side of the mountain, which is downwind from the windward, side is in a “rain shadow”. The leeward side of the mountain, which is downwind from the windward, side is in a “rain shadow”. –The air on the leeward side tends to be drier than the windward side, where the rain or snow falls, after being removed from the humid wind

13 Seasons Most places on Earth outside of the tropics have four seasons Most places on Earth outside of the tropics have four seasons –Winter –Spring –Summer –Autumn (fall) Earth is tilted at an angle of 23.5° on its axis. Earth is tilted at an angle of 23.5° on its axis.

14 The Reason for Seasons! Seasons are caused by the tilt of Earth’s axis as Earth travels around the sun. Seasons are caused by the tilt of Earth’s axis as Earth travels around the sun. Axis – the imaginary line that passes through Earth’s center and the N.& S. Poles Axis – the imaginary line that passes through Earth’s center and the N.& S. Poles Because of this tilt the Sun’s rays hit the: Because of this tilt the Sun’s rays hit the: –Equator more directly –Poles at an angle

15 Days Earth’s rotation (spinning on its axis) causes day and night. Earth’s rotation (spinning on its axis) causes day and night. Earth rotates from West to East (Sun rises in the east and sets in the west) counterclockwise. Earth rotates from West to East (Sun rises in the east and sets in the west) counterclockwise. Each rotation takes approximately 24 hours. Each rotation takes approximately 24 hours. We know all this because of Astronomy, the study of the moon, stars, and other objects in space. We know all this because of Astronomy, the study of the moon, stars, and other objects in space.

16 Rotation…Rotation…Rotation The Earth rotates on its axis at a speed of 30 km/sec. The Earth rotates on its axis at a speed of 30 km/sec. 1,600 km/hour or 2,580 mph! 1,600 km/hour or 2,580 mph!

17 Years The Earth travels on a path around the Sun called an orbit. The Earth travels on a path around the Sun called an orbit. As the Earth rotates it also revolves As the Earth rotates it also revolves Revolution is the movement of one object around another object. Revolution is the movement of one object around another object. The Earth takes about days or one year to revolve around the sun. The Earth takes about days or one year to revolve around the sun. The Earth’s orbit is like a flattened circle, not perfectly round. The Earth’s orbit is like a flattened circle, not perfectly round.

18 Earth’s Tilt When the north end is tilted toward the Sun, it is summer in the Northern Hemisphere (winter in Southern Hemisphere) When the north end is tilted toward the Sun, it is summer in the Northern Hemisphere (winter in Southern Hemisphere) When the southern end it tilted toward the Sun, it is summer in the Southern Hemisphere (winter in Northern Hemisphere) When the southern end it tilted toward the Sun, it is summer in the Southern Hemisphere (winter in Northern Hemisphere)

19 Calendar Since the orbit takes days, we have adjusted our calendar to make up for the ¼ day. We use the Roman Calendar Since the orbit takes days, we have adjusted our calendar to make up for the ¼ day. We use the Roman Calendar Every 4 years we have a Leap Year. The leap day is February 29 th ! Every 4 years we have a Leap Year. The leap day is February 29 th ! This year was a Leap Year (2008). This year was a Leap Year (2008). Other years always have Other years always have –7 months – 31 days –4 months – 30 days –1 month – 28 days

20 Summer and Winter Summer and Winter are NOT affected by changes in Earth’s distance from the Sun Summer and Winter are NOT affected by changes in Earth’s distance from the Sun Earth is at its greatest distance from the Sun during the summer! Earth is at its greatest distance from the Sun during the summer!

21 Solstices Two days each year when the noon Sun is directly overhead in the N. Hemisphere at 23.5° N or 23.5° S Two days each year when the noon Sun is directly overhead in the N. Hemisphere at 23.5° N or 23.5° S Winter Solstice - in the Northern Hemisphere, the Sun is overhead at this angle on December 21 st (we have shortest day) Winter Solstice - in the Northern Hemisphere, the Sun is overhead at this angle on December 21 st (we have shortest day) Summer Solstice - in the summer (Northern Hemisphere), the Sun is overhead at this angle on June 21 st (we have longest day) Summer Solstice - in the summer (Northern Hemisphere), the Sun is overhead at this angle on June 21 st (we have longest day)

22 Equinox Means equal day and equal night! Means equal day and equal night! When the noon Sun is directly overhead at the equator When the noon Sun is directly overhead at the equator Occurs two times per year when we have 12 hours of daylight and 12 hours of darkness Occurs two times per year when we have 12 hours of daylight and 12 hours of darkness Vernal Equinox (spring) – March 21st Vernal Equinox (spring) – March 21st Autumnal Equinox (fall) – September 23rd Autumnal Equinox (fall) – September 23rd

23 ADD MOON PHASES, Eclipses, TIDES

24 Ozone Depletion Ozone is a gas in the stratosphere, a high layer of the atmosphere, that absorbs most of the ultraviolet radiation that strikes Earth from the sun. Ozone is a gas in the stratosphere, a high layer of the atmosphere, that absorbs most of the ultraviolet radiation that strikes Earth from the sun. Chemicals produced by humans have been damaging the ozone layer, chloroflourocarbons (CFC’s) are the main cause. Chemicals produced by humans have been damaging the ozone layer, chloroflourocarbons (CFC’s) are the main cause.

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