1. Meteorology

2. Characteristics of the Atmosphere Terms: atmosphere, air pressure, troposphere, stratosphere, mesosphere, thermosphere

3. Characteristics of the Atmosphere Describe the composition of Earth’s atmosphere. What does the name of each atmospheric layer mean? Why doesn’t the thermosphere feel hot?

4. The Composition of the Atmosphere The atmosphere is a mixture of gases that surrounds Earth. Makes conditions on Earth suitable for living things Gases keep the atmosphere on Earth’s surface warm enough for water to exist as a liquid, protects against dangerous radiation, prevents Earth’s surface from being hit by most meteoroids or chunks of rock from outer space. Gases –Nitrogen 78% –Oxygen 21% –Other gases 1% –Water vapor <1% Solids –Dust, volcanic ash, salt, dirt, smoke Liquids –water

5. Atmospheric Pressure and Temperature As altitude increases, air pressure decreases –Air pressure is strongest at Earth’s surface because more air is above you. Atmospheric composition affects air temperature –Temperature differences result from the way solar energy is absorbed as it moves through the atmosphere –High % of gases that absorb solar energy= warmer –Less gases that absorb solar energy = cooler

6. Layers of the Atmosphere Based on temperature changes: –Troposphere: layer in which we live; contains almost all of the weather, carbon dioxide, water vapor, clouds, air pollution, and life-forms –Stratosphere: gases are layered and don’t mix; contains the ozone layer; protects life by absorbing harmful UV radiation –Mesosphere: middle layer; the coldest layer; most meteoroids burn up here, producing meteoroid trails –Thermosphere: temperature increases; does not feel hot; outer most part of atmosphere; no definite outer limit

7. Summary Nitrogen and oxygen make up most of Earth’s atmosphere. Air pressure decreases as altitude increases. The composition of atmospheric layers affects their temperature. The troposphere is the lowest atmospheric layer. It is the layer in which we live. The stratosphere contains the ozone layer, which protects us from harmful radiation. The mesosphere is the coldest atmospheric layer. Meteoroids burn up in this layer. The thermosphere is the uppermost layer of the atmosphere.

8. #1 Quick Check Why does the temperature of different layers of the atmosphere vary? A.Because air temperature increases as altitude increases B.Because the amount of energy radiated from the sun varies C.Because of interference by humans D.Because of the composition of gases in each layer

9. #2 Quick Check What is the most abundant gas in the atmosphere? a.oxygen b.hydrogen c.nitrogen d.carbon dioxide

10. #3 Quick Check A major source of oxygen for the earth’s atmosphere is a. sea water. b. the sun. c. animals d. plants

11. #4 Quick Check The bottom layer of the atmosphere where almost all weather occurs, is the a.stratosphere b.troposphere c.thermosphere d.mesosphere

12. #5 Quick Check The ozone layer is located in the a.stratosphere b.troposphere c.thermosphere d.mesosphere

13. Heat and Weather Patterns Weatherclimate visible lightair masses sea breeze Convection currents Density land breeze

14. Heat and Weather Patterns What is weather? What is climate? What is a sea breeze? What is a land breeze? What are air masses?

15. Heat and Weather Patterns Weather and Climate Weather is the process in the atmosphere that changes over a short period of time. Climate is the weather that is in place most of the time or over a long period of time. Is it Climate or Weather? –What’s the weather like most of the time where you live?

16. The Sun’s Energy Nearly all the energy in Earth’s atmosphere comes from the sun. Most of the energy from the sun reaches Earth in the form of visible light and infrared radiation, with a small amount of ultraviolet radiation. Visible light is energy you can see.

17. The Sun’s Energy Earth changes infrared radiation into heat energy. Ultraviolet radiation causes sunburns, skin cancer, and eye damage. Some of the sun’s energy reaches Earth’s surface and is reflected back into the atmosphere. Some of the energy is absorbed by the land and water and changed into heat.

18. The Sun’s Energy Land heats up and cools down faster than water. Water heats up more slowly than land does, but holds the heat longer. Air heats up unevenly. Warm air becomes less dense and rises. Cooler air becomes more dense and sinks.

19. The Sun’s Energy Wind that blows from an ocean or lake onto land is known as a sea breeze. The flow of air from land to a body of water is called a land breeze. Convection currents transfer heat from one place to another through a liquid or a gas. In Earth’s atmosphere, convection currents carry warm air upwards and cool air downwards. This is because of the uneven heating of Earth’s surface.

20. The Sun’s Energy Huge chunks of warm and cold air are called air masses. Air masses move sideways across continents and oceans. Clouds and storms form when these masses run into each other. When a cold air mass meets a warm air mass, thunderstorms may appear.

21. Quick Check Land absorbs radiation from the sun A. slower than water. B. faster than water. C. at the same rate as water. D. almost never.

22. Quick Check In the atmosphere, what happens in a convection current? A. cool air and warmer air both rise B. cool air and warmer air both fall C. cool air rises and warmer air falls D. cool air falls and warmer air rises

23. Quick Check What does solar (infrared) radiation produce on Earth? A. light B. heat C. land D. water

24. Quick Check In which direction does a sea breeze move? A. toward the land B. toward the sea C. up D. down

25. Quick Check How are climate and weather alike? A. They both occur over short periods of time. B. They both occur over long periods of time. C. They both are affected by radiation from the sun. D. They are both caused by even heating of Earth’s surface.

26. What are Air Masses and Fronts? (Chapter 16 Section 2) Terms: air mass, front, cyclone, anticyclone,

27. What are air masses and fronts? P. 490 What are the major air masses that influence the weather in the U.S.? What is one source region of a maritime polar air mass? What are the characteristics of an air mass whose two-letter symbol is cP? What are the four major types of fronts?

28. Air Masses Air masses are large bodies of air where temperature and moisture content are constant throughout. Moisture content and temperature of a mass are determined by the area over which the air mass forms. These areas are called source regions.

29. Types of Air Masses maritime (m) – forms over water; wet Continental (c) – forms over land; dry Polar (P) – forms over the polar regions; cold Tropical (T) – develops over the tropics; warm

30. Cold Air Masses Three polar air masses: –Continental polar (cP) forms over northern Canada; brings extremely cold weather during winter; brings cool dry weather during summer –Maritime polar (mP) forms over North Pacific Ocean; cool, very wet; rain and snow during winter; foggy during summer –Maritime polar (mP) forms over North Atlantic Ocean; cool, cloudy and precipitation during winter; mild, cloudy during summer.

31. Warm Air Masses There are three warm air masses that affect the U.S. –Maritime tropical (mT) forms over warm water in the Pacific ocean –(mT) forms over the Gulf of Mexico and the Atlantic Ocean; brings hot, humid weather and hurricanes and thunderstorms during the summer; In winter, brings mild, cloudy weather –Continental Tropical (cT) forms deserts of Mexico and Southwestern U.S.; brings clear, hot, dry weather during summer

32. Fronts The boundary between air masses of different densities and different temperatures –Cold Front – cold air moves under warm air; brings thunderstorms –Warm Front – warm air moves over cold air; brings drizzly rain followed by clear and warm weather.

33. Fronts Occluded Front – warm air mass is caught between two colder air masses. Brings cool temperature and large amounts of rain. Stationary Front – cold air mass meets warm air mass; remain separate; not enough energy to move warm air above cold air mass; can bring many days of cloudy, wet weather.

34. Air Pressure and Weather Cyclones – areas in the atmosphere that has lower pressure than the surrounding areas and has winds that spiral toward the center. Brings clouds and rain. Anticyclones – the rotation of air around a high pressure center in the direction opposite to Earth’s rotation. Brings dry, clear weather.

35. Quick Check What kind of front forms when a cold air mass displaces a warm air mass? A. a cold front B. a warm front C. an occluded front D. a stationary front

36. Quick Check A maritime tropical air mass contains A. cold, dry air. B. warm, dry air. C. warm, wet air. D. cold, wet air.

37. Quick Check A front that forms when a warm air mass is trapped between two cold air masses and is forced to rise is a(n) A. stationary front. B. occluded front. C. warm front. D. cold front.

38. Global Wind Systems and Weather Events Global Winds Tornadoes Thunderstorms Cumulonimbus clouds Low density High density Low pressure High pressure Air pressure

39. How would you distinguish between local winds and global winds? What combination of air produces global winds? What makes global winds curve rather than move in straight lines? What properties of air near the ground are likely to produce a thunderstorm? What combination of properties describes cold air?

40. Global Winds Wind is the horizontal movement of air from an area of high pressure to an area of low pressure. All winds are caused by differences in air pressure. Local winds are winds that blow over short distances. Local winds are caused by unequal heating of Earth’s surface within a small area.

41. Global Winds The unequal heating of Earth’s atmosphere by sunlight produces global winds. The combination of high-pressure polar air and low-pressure equatorial air produces global winds. The angle at which sunshine strikes Earth’s surface in MAINLY responsible for the unequal heating of Earth’s surface.

42. Global Winds Air moves from areas of high pressure to areas of low pressure. Dense, high-pressure air over the poles sinks and moves towards the low-pressure air over the equator. Less dense, low-pressure air over the equator rises and moves toward the poles. These movements of air are global winds. Earth’s spin on its axis makes these winds move along a curved path (Coriolis effect). Northern Hemisphere global winds curve clockwise. Southern Hemisphere global winds curve counterclockwise.

43. Tornadoes and Thunderstorms Differences in air pressure can also produce powerful local winds and storms. The low density, warm air will form clouds when it reaches colder air in the sky. As low density moisture rises high in the sky, it may freeze into particles that are electrically charged. These charged particles can produce lightning and thunder.

44. Tornadoes and Thunderstorms Moist, low pressure air near the ground produce thunderstorms. Thunderstorms form within large cumulonimbus clouds, also known as thunderheads. Tornadoes are swiftly turning, very low-pressure funnels of air. They produce the fastest moving winds on Earth. Tornadoes develop in low, heavy cumulonimbus clouds. Most likely to occur in spring and summer, often in the late afternoon when the ground is warm. Tornadoes occur more often in the U.S. than in any other country.

45. Quick Check What combination produces global winds? A. low-pressure polar air and low-pressure equatorial air B. low-pressure polar air and high-pressure equatorial air C. high-pressure polar air and high-pressure equatorial air D. high-pressure polar air and low-pressure equatorial air

46. Quick Check What is MAINLY responsible for the unequal heating of Earth’s surface? A. the distance of the sun from different parts of Earth B. the angle at which sunshine strikes Earth’s surface C. the material on Earth’s surface D. changes in the amount of energy the sun puts out

47. Quick Check What makes global winds curve rather than move in straight lines? A. differences in air pressure B. differences in density C. differences in temperature D. Earth’s rotation on its axis

48. Quick Check What properties of air near the ground are likely to produce a thunderstorm? A. moist, low pressure B. dry, low pressure C. moist, high pressure D. dry, high pressure

49. Quick Check Which combination of properties describe cold air? A. high density and low pressure B. low density and low pressure C. high density and high pressure D. low density and high pressure

50. Heat and Weather Patterns Tropical stormsHurricanes Tropical depression ClockwiseCounterclockwise Eye of a hurricane

51. How does evaporation of water affect weather and the formation of hurricanes? What is the source of a hurricane’s energy? What is the general name for a powerful tropical storm? Where are tropical storms born? What happens when moist air rises high into the sky?

52. Moisture and Weather Patterns Tropical storms are born over warm water near the equator. Very large and powerful tropical storms with spinning winds are called tropical cyclones. In the Atlantic Ocean and the eastern Pacific Ocean, tropical cyclones are called hurricanes. In the northwest Pacific Ocean, they are called typhoons.

53. Moisture and Weather Patterns Energy from the sun warms ocean water. Energy absorbed by the ocean water causes the water on the surface to evaporate. The warm, evaporated water rises. This produces an area of low pressure called a tropical depression. This is when clouds begin to form.

54. Moisture and Weather Patterns The air in the center of a depression in the Northern Hemisphere begins to spin counterclockwise. In the Atlantic Ocean, global winds push the storm westward. As the storm continues to move over warm water, heat from the water feeds it. As its air pressure drops lower its winds move faster and faster.

55. Moisture and Weather Patterns A hurricane has a typical shape. The eye of a hurricane is a place of very low pressure with no clouds above it. In the eye, it is very calm and sunny. The most violent winds in a hurricane form the wall of the hurricane’s eye. Eventually, a hurricane will travel over cooler water or land. Once this happens, the hurricane can no longer feed on heat energy from warm water.

56. Quick Check What is the source of a hurricane’s energy? A. warm, moist air evaporating from the sea B. cool, moist air evaporating from the sea C. warm, dry air evaporating from the sea D. warm, moist air condensing from the sea

57. Quick Check The general name for a powerful tropical storm is a A. tropical depression. B. tropical cyclone. C. hurricane. D. typhoon.

58. Quick Check Where are tropical storms born? A. over water near Earth’s poles B. over land near Earth’s poles C. over water near the equator D. over land near the equator

59. Quick Check What happens when moist air rises high into the sky? A. It cools and evaporates B. It cools and condenses, forming clouds C. It warms and evaporates D. It warms and condenses

60. Quick Check The eye of a hurricane has A. low pressure and high winds. B. low pressure and no winds. C. high pressure and high winds. D. high pressure and no winds.