1. Weather versus Climate
Composition of the Atmosphere
Weather versus Climate
Weather - the state of the atmosphere at any given time and place. Constantly changing
Climate - weather patterns and averages that have been collected over many years. Climate helps describe a place or region.

2. Factors that Affect Climate
Atmospheric Circulation – Wind currents affect climate by transferring heat from the tropics to the polar regions

3. 17.3 Temperature Controls Why Temperatures Vary
Some factors other than latitude that exert a strong influence on temperature include:
Altitude – cooler temperatures at higher altitudes
cloud cover – lower temperature when cloudy (albedo)

4. 17.3 Temperature Controls Why Temperatures Vary
 Cloud Cover and Albedo
• Albedo is the fraction of total radiation that is reflected by any surface.
• Many clouds have a high albedo and therefore reflect back to space a significant portion of the sunlight that strikes them.

5. Clouds Reflect and Absorb Radiation
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6. 20.1 Air Masses Air Masses and Weather  Air Masses
• An air mass is an immense body of air that is characterized by similar temperatures and amounts of moisture at any given altitude.
 Movement of Air Masses
• As it moves, the characteristics of an air mass change and so does the weather in the area over which the air mass moves.

7. Frigid Canadian Air Mass Moves Southward
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8. 20.1 Air Masses Classifying Air Masses
 In addition to their overall temperature, air masses are classified according to the surface over which they form.

9. Air Masses Are Classified by Region
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10. 20.2 Fronts Formation of Fronts
 When two air masses meet, they form a front, which is a boundary that separates two air masses.

11. 20.2 Fronts Types of Fronts  Warm Fronts  Cold Fronts
• A warm front forms when warm air moves into an area formerly covered by cooler air.
 Cold Fronts
• A cold front forms when cold, dense air moves into a region occupied by warmer air.

12. Formation of a Warm Front
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13. Formation of a Cold Front
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14. 20.3 Severe Storms Thunderstorms
 A thunderstorm is a storm that generates lightning and thunder. Thunderstorms frequently produce gusty winds, heavy rain, and hail.

15. 20.3 Severe Storms Tornadoes
 Tornadoes are violent windstorms that take the form of a rotation column of air called a vortex.

16. Formation of a tornado
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17. This is your last power point for the year!!
YAY! - - you made it!