1. Weather & Climate Objectives: 1) Sun’s affects
2) Understand atmospheric pressure
3) Global wind belts affect weather/climate
4) Oceans affect on weather/climate

2. Opening Activity
1) What would happen if, for one week, all the winds in the world were still?
Define Terms on page 41
Possible Answers: Temperature differences would become extreme
air pollution would get worse
ocean waves would calm

3. What is what?
Weather is the condition of the atmosphere at a given time and place
Weather conditions in a geographic region over a long time are called climate.

4. The Sun Solar Energy Greenhouse effect Global Warming
½ reflected back in space/atmosphere
½ absorbed and converted to heat = temperature
Greenhouse effect
Trapped heat
Global Warming
Increased carbon emissions
Debate continues

5. Atmospheric Pressure Atmosphere has weight
Called atmospheric pressure or air pressure
As elevation increases air pressure decreases
Airplanes
Mountain climbers
Low pressure: hot air rises, cool and forms clouds
Cyclones
Unstable weather
High pressure: cold air sinks to earth, heats up
Clear skies
Extreme heat or cold

6. Four Air Pressure Zones
The Four
Equatorial Low
Subtropical Highs
Subpolar Lows
Polar Highs
Carry air back and forth from equator to Poles
From equator – warm air rises, then cools and sinks as it nears Poles

7. Wind Belts Air pressure affects wind patterns.
Wind is the horizontal flow of air, moving from low to high pressure areas moving cold or hot air
Wind moves hot and cold air across earth’s surface
Types of winds
Prevailing winds
Westerlies, Easterlies
Jet Stream, Upper atmosphere
Doldrums
Between tropics
Fronts
Two air masses meet

8. Jet Stream
During WWII, Japan used the jet stream that flows across the Pacific to North America to deliver bombs
Called Fu-go, which means “wind ship weapon”
As far as Michigan
Today pilots use jet stream to save fuel and time.

10. On your own
Locate the following locations on page S23, and identify the types of winds likely to be found in each of these areas:
Greenland
New York, New York
The Galapagos Islands
Tasmania
Outer edges of Antarctica
Answers: Greenland and Antartica – cold polar easterlies; New York City and Tasmania – Westerlies; Galapagos Islands – no prevailing winds

11. Oceans and Currents Oceans affect climate
Land near oceans do not have great temp ranges
San Fran. vs. Kansas City
Currents move heat back and forth between Tropics and Polar Regions
Maintains Earth’s energy balance
Gulf Stream
Warm current
Effect of Europe

12. Closing Thought
During the 1700’s sailors dubbed the northern edge of the northeast trade winds belt the horse latitudes. Ships caught in the region would often run low on supplies. To save water, the horses would be thrown overboard so the people could survive.

13. Precipitation Elevation Storms
Weather Factors
Precipitation
Elevation Storms

14. Precipitation
Evaporation = process by which water changes from liquid to gas.
Most water vapor that becomes rain comes from oceans
Humidity = amount of water vapor in the air
The higher the temp. the more water vapor the air can hold
When air cools it will not be able to hold water vapor. At this point condensation occurs
Condensation = water vapor changing from gas to liquid
Appears as clouds, dew, fog, and mist

15. Forms of Precipitation Four common forms of precipitation are rain, snow, sleet, and hail

16. Precipitation varies around the world
Precipitation varies around the world. Generally highest in low-pressure zones. These zones generally in the middle latitudes

17. Elevation Effects Increase in elevation causes a drop in temperature.
Temp. drops 3.5 F per 1,000 feet of elevation.
May be warm at the base of the mountain with snow covered peak.

18. Mountain Effects
Orographic Effect – moist air pushes against a mountain.
Rising air cools and condenses, forming clouds and precipitation
Side of mountain facing wind receives great deal of moisture (windward side)
Side facing away is leeward side
As air moves down leeward side it warms and dries
This drier air is called a rain shadow
Deserts are often located

19. Storms Storms are sudden and violent weather events
Most middle latitude storms occur along a polar front – form when cold dry polar air mixes with warm air from tropics
Move from west to east
Middle-latitude storms may produce tornadoes.
The USA has most tornadoes

20. Storms Storms in the tropics differ from middle latitudes
No cold air present, lack fronts
Move westward with trade winds
Hurricanes – violent tropical storms
Begin over warm tropical seas
Weaken as they move inland
Winds up to 155 mph
Typhoons: Hurricanes in the W. Pacific Ocean, can create dangerously high waves