AIR MASSES• A large body of air (thousands  of miles)• Changes in weather are caused  by movements of air masses• As an ai...
Classification• Air masses are named from  the area where they come  from.• Classified according to :  temperature & moist...
• Tropical- HOT air mass  formed in tropics• Polar- COLD air mass formed  near poles• Maritime- air mass formed  over ocea...
TYPES OF AIR MASSES1. MARITIME TROPICAL2. MARITIME POLAR3. CONTINENTAL POLAR4. CONTINENTAL   TROPICAL
Warm, humid air mass formed  over ocean near equator.Summer = hot humid weatherWinter = heavy rain/snowfall
Cool, humid air masses formed over ocean near polesSummer = cool temps, fog, rainWinter = snow, cold temps
• Hot, dry air masses formed  mostly in the summer over dry  lands of SW & N Mexico.
Large, cold air mass formed over land in Canada & Alaska.Winter- extremely cold, dry air.Summer- cold, dry air temps
• Prevailing Westerlies push air  masses west to east.• Jet Stream- blow west to east• Fronts- boundaries between air  mas...
Chapter 17 Lesson 1Review          page 581• What are the two characteristics of an air  mass that you need to know in ord...
• Colliding air masses can form  4 types of fronts: 1. Cold fronts 2. Warm fronts  3. Stationary fronts  4. Occluded fronts
• forms when a cold air mass  meets & pushes under a warm  air mass.• Warm air cools, clouds form,  & heavy rain. (thunder...
• Forms when a warm air mass  moves over a cold air mass.• Rain showers then hot, humid  weather.
• Warm air mass meets a cold  air mass & no movement  occurs. Produces rain &  clouds.
• When a warm air mass is  caught between 2 colder air  masses. Warm air cut off.• Produces clouds, rain/snow.
• A center of low air pressure,  winds spiral inward.• As air rises in a cyclone, the  air cools forming clouds &  precipi...
•High pressure areas of dry air where winds spiral outward. (clockwise)•Descending air in an anticyclone causes dry, clear...
STORM• A violent disturbance in  the atmosphere
• A small storm often  accompanied with heavy  precipitation & thunder &  lightning.• Form in large cumulonimbus  clouds c...
• On hot, humid days, warm air  rises rapidly, & cools forming  cumulonimbus clouds.• This movement of air creates  updraf...
Areas of (+)/(-) charges build up in storm clouds. It is a sudden discharge of electricity between 2 clouds or the cloud a...
Light travels faster than sound. Lightning heats air. Heated air expands rapidly which results in sound waves (thunder).
T-Storm Damage• Heavy rains which can lead  to floods.• Lightning, Hail, & winds  can cause damage.
• Whirling, funnel shaped cloud  that reaches down from a  storm cloud to touch earth’s  surface.• Warmth & Moisture feed ...
• Warm, humid air meets cold, dry  air. A squall line of thunderstorms  develop which can develop into a  tornado.• Warm a...
• Tornado Alley- Mid-West US• This is where the conditions  are the best- warm, humid air  from Mexico mixes with cold,  d...
• Tornadoes occur most frequently  in the US• Damage comes from strong winds  & flying debris.
• Tornadoes are ranked on the  Fujita Scale (by the amount of  damage they cause.)• F0 light damage to F5 extreme  damage....
• A tropical cyclone that has  winds of 119kmh or higher.• Forms in the Atlantic, Pacific,  & Indian Oceans. In western  P...
HURRICANE FORMATION• It begins over warm ocean water  as a low-pressure area (tropical  disturbance).• It grows from a dis...
• It draws energy from warm,  humid air at ocean’s surface.• Warm air rises to form clouds,  more air is drawn into the  s...
• Cool, dry air sinks into the  center (eye) of the hurricane.• Hurricanes last longer than  other storms- usually a week ...
• Year round, most precipitation  begins in the clouds as snow.
• Cold, dry air moves across  warmer water picking up water  vapor & heat from the water.  Once the air reaches the other ...
• In New York, Buffalo &  Rochester are 2 of the  snowiest cities in the US  because of Lake-Effect  Snow.
Snowstorm Safety• Find shelter from the wind.• It can be dangerous because  high winds/snow limit your  vision so you can ...
Meteorologists• Scientists who study the causes  of weather & try to predict it.• Meteorologists use maps,  charts, & comp...
• Lines joining places that have the same temps.
• Lines joining areas with the same air pressure.
TECHNOLOGY• Has improved the accuracy of  weather forecasts.• Weather balloons carry  instruments into the  troposphere & ...
• Weather Satellites- orbit earth  in the thermosphere, cameras  make images of the earth’s  surface, clouds, & storms  wh...
• Computer Forecasts- gathers  weather data from a large area  then the computer works  through thousands of  calculations...
Chapter 17 7th es
Chapter 17 7th es
Chapter 17 7th es
Chapter 17 7th es
Chapter 17 7th es
Chapter 17 7th es
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Chapter 17 7th es

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Chapter 17 7th es

  1. 1. AIR MASSES• A large body of air (thousands of miles)• Changes in weather are caused by movements of air masses• As an air mass moves away, temp & humidity change.
  2. 2. Classification• Air masses are named from the area where they come from.• Classified according to : temperature & moisture content.
  3. 3. • Tropical- HOT air mass formed in tropics• Polar- COLD air mass formed near poles• Maritime- air mass formed over oceans, WET• Continental- air mass formed over land, DRY
  4. 4. TYPES OF AIR MASSES1. MARITIME TROPICAL2. MARITIME POLAR3. CONTINENTAL POLAR4. CONTINENTAL TROPICAL
  5. 5. Warm, humid air mass formed over ocean near equator.Summer = hot humid weatherWinter = heavy rain/snowfall
  6. 6. Cool, humid air masses formed over ocean near polesSummer = cool temps, fog, rainWinter = snow, cold temps
  7. 7. • Hot, dry air masses formed mostly in the summer over dry lands of SW & N Mexico.
  8. 8. Large, cold air mass formed over land in Canada & Alaska.Winter- extremely cold, dry air.Summer- cold, dry air temps
  9. 9. • Prevailing Westerlies push air masses west to east.• Jet Stream- blow west to east• Fronts- boundaries between air masses, changeable weather & storms develop along fronts.
  10. 10. Chapter 17 Lesson 1Review page 581• What are the two characteristics of an air mass that you need to know in order to classify it?• What happens when a warmer air mass pushes a cooler air mass?• What type of weather system brings calm, clear weather?
  11. 11. • Colliding air masses can form 4 types of fronts: 1. Cold fronts 2. Warm fronts 3. Stationary fronts 4. Occluded fronts
  12. 12. • forms when a cold air mass meets & pushes under a warm air mass.• Warm air cools, clouds form, & heavy rain. (thunderstorms).• cool weather
  13. 13. • Forms when a warm air mass moves over a cold air mass.• Rain showers then hot, humid weather.
  14. 14. • Warm air mass meets a cold air mass & no movement occurs. Produces rain & clouds.
  15. 15. • When a warm air mass is caught between 2 colder air masses. Warm air cut off.• Produces clouds, rain/snow.
  16. 16. • A center of low air pressure, winds spiral inward.• As air rises in a cyclone, the air cools forming clouds & precipitation.
  17. 17. •High pressure areas of dry air where winds spiral outward. (clockwise)•Descending air in an anticyclone causes dry, clear weather.
  18. 18. STORM• A violent disturbance in the atmosphere
  19. 19. • A small storm often accompanied with heavy precipitation & thunder & lightning.• Form in large cumulonimbus clouds called thunderheads.
  20. 20. • On hot, humid days, warm air rises rapidly, & cools forming cumulonimbus clouds.• This movement of air creates updraft & downdraft winds.
  21. 21. Areas of (+)/(-) charges build up in storm clouds. It is a sudden discharge of electricity between 2 clouds or the cloud and the ground. Electric energy is released.
  22. 22. Light travels faster than sound. Lightning heats air. Heated air expands rapidly which results in sound waves (thunder).
  23. 23. T-Storm Damage• Heavy rains which can lead to floods.• Lightning, Hail, & winds can cause damage.
  24. 24. • Whirling, funnel shaped cloud that reaches down from a storm cloud to touch earth’s surface.• Warmth & Moisture feed it• Season: late spring/early summer
  25. 25. • Warm, humid air meets cold, dry air. A squall line of thunderstorms develop which can develop into a tornado.• Warm air rises rapidly & begins to rotate. The cloud will then start to descend to earth in a funnel.
  26. 26. • Tornado Alley- Mid-West US• This is where the conditions are the best- warm, humid air from Mexico mixes with cold, dry air from Canada.
  27. 27. • Tornadoes occur most frequently in the US• Damage comes from strong winds & flying debris.
  28. 28. • Tornadoes are ranked on the Fujita Scale (by the amount of damage they cause.)• F0 light damage to F5 extreme damage.• F4 F5 tornadoes account for only 1% of all tornadoes.
  29. 29. • A tropical cyclone that has winds of 119kmh or higher.• Forms in the Atlantic, Pacific, & Indian Oceans. In western Pacific- typhoons.
  30. 30. HURRICANE FORMATION• It begins over warm ocean water as a low-pressure area (tropical disturbance).• It grows from a disturbance to a tropical storm and maybe to a hurricane.
  31. 31. • It draws energy from warm, humid air at ocean’s surface.• Warm air rises to form clouds, more air is drawn into the system.• Storms bands, high winds, & heavy rains spiral around a center.
  32. 32. • Cool, dry air sinks into the center (eye) of the hurricane.• Hurricanes last longer than other storms- usually a week or longer.
  33. 33. • Year round, most precipitation begins in the clouds as snow.
  34. 34. • Cold, dry air moves across warmer water picking up water vapor & heat from the water. Once the air reaches the other side of the lake, air condenses & falls as snow.
  35. 35. • In New York, Buffalo & Rochester are 2 of the snowiest cities in the US because of Lake-Effect Snow.
  36. 36. Snowstorm Safety• Find shelter from the wind.• It can be dangerous because high winds/snow limit your vision so you can get lost easily & you can lose a lot of body heat out in the cold.
  37. 37. Meteorologists• Scientists who study the causes of weather & try to predict it.• Meteorologists use maps, charts, & computers to analyze weather & prepare weather forecasts.
  38. 38. • Lines joining places that have the same temps.
  39. 39. • Lines joining areas with the same air pressure.
  40. 40. TECHNOLOGY• Has improved the accuracy of weather forecasts.• Weather balloons carry instruments into the troposphere & stratosphere to measure temp., air pressure, & humidity.
  41. 41. • Weather Satellites- orbit earth in the thermosphere, cameras make images of the earth’s surface, clouds, & storms which get sent to meteorologists to analyze.
  42. 42. • Computer Forecasts- gathers weather data from a large area then the computer works through thousands of calculations using equations from weather models to make forecasts for 12, 24, & 36 hours. Each one builds on the previous forecasts.

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