File
Air Currents
Chapter 4 lesson 3
How does uneven heating of Earth’s surface result in air movement?
The Sun’s energy warms the Earth
The amount of energy an area gets depends A LOT on the Sun’s angle.
(Areas closer to the equator get more
DIRECT sunlight than areas closer to the poles!) less direct, light spread out
More direct, light concentrated less direct, light spread out
Remember : The warmer the air is, the lower the density .
“ The Tropics ” – areas near the equator-
Sunlight strikes Earth’s surface at an angle of about 90 degrees.
Air is less dense, has less pressure
Land, water and air (in this area) stay warm.
“Polar”- areas near the north and south pole-
Sunlight strikes surface at a low angle.
Sunlight is spread out over a larger area
The air, in this area has higher pressure.
Land, water and air stays cold.
• The difference between the high pressure of the cold area, and the low pressure of the warm air creates global WIND belts.
• Wind travels from areas of HIGH pressure TO areas of LOW pressure
Westerlies: steady winds that flow from west to East
W
Westerlies: steady winds that flow from west to East
Global Wind Belts
Polar easterlies: cold winds that blow from east to west
Trade Winds:
Steady winds that Flow east to west
E
Trade Winds:
Steady winds that Flow east to west
Polar easterlies: cold winds that blow from east to west
Jet Streams
• Jet streams are narrow bands of high winds up to
300km/h), near the top of the troposphere.
• Jet streams flow around
Earth from West to East, making large loops to the north or south.
• Jet streams move air masses, so they influence weather.
• These winds are more
UNPREDICTABLE than prevailing winds (trade winds, westerlies, and polar easterlies)
Local Winds
Sea Breeze
• Wind that blows from sea to land, due to local temperature and pressure differences
Land Breeze
• Wind that blows from land to sea, due to local temperature and pressure differences.
Ch. 4, lesson 3 vocabulary
•
Wind
•
Trade winds
•
Westerlies
•
Polar easterlies
•
Jet stream
•
Sea breeze
•
Land breeze
Prevailing Winds/ Jet streams
Paper plate Project
Materials:
• 2 Paper plates
• Markers/ colored pencils
• Scissors
• Text book/ interactive notebook
Required components:
1) Draw the lines of latitude
2) Degrees latitude
3) N/ E/ S/ W directions
4) Label the prevailing winds
5) Write the definition/ description of the prevailing winds
6) Draw arrows to show wind direction
7) Draw the jet streams
Rubric for project
15 points
10 points
5 points
Rubric
Labeling
Accurate descriptions
Arrows in correct direction
Latitudes correct
All components presents neatness
30 points TOTAL
