Download Causes of Prevailing Winds

7.1 – Air Currents (Winds)
p. 273 – 274
wind = movement of air, from high pressure to low pressure
o Figure 7.8 on p. 273
 caused by the uneven heating of Earth’s surface
 disperses heat energy throughout the atmosphere from
warm areas to cooler areas
 causes ocean currents to move in a particular direction
prevailing winds = winds that blow in constant directions
around the world, that affect large areas
o ex: westerlies & trade winds
 Columbus took advantage of these to sail
from Europe to America and back!
 pilots use these to save on fuel
o Figure 7.9 on p. 274
Coriolis effect = the apparent curve of a moving object in a
rotating system
 noticed least at the equator and most near the poles
 causes the curve in prevailing wind patterns
jet stream = high speed winds in the upper regions of the
atmosphere
 move from west to east
 steer most weather systems
(the polar jet stream affects
Canada)
 as our climate has changed,
so has the path the polar jet
stream takes across America
o makes it tough to
predict weather
Causes of Prevailing Winds
 caused by a combination of convection currents and
Earth’s eastward rotation
 affected by changing seasons
Effects of Winds on Climate
 help distribute large amounts of solar  from equator
toward colder parts of the world (poles) by air and water
 currents at the surface of the oceans is driven by air
currents blowing over the water
o  from moving air is transferred to the surface of
the water, causing the water to move
 this is why ocean currents move in the same direction as
air currents (winds)
 carry moisture, helping to cause different types of
precipitation
o when air masses meet, one mass slides above the
other
o the rising air cools, condenses, and forms
precipitation
Demonstrate the Coriolis effect using the spinner!
Questions
Knowledge/Understanding
1. Define prevailing winds.
2. Give an example of a local wind that we learned about in yesterday’s lesson.
3. a) What is the Coriolis Effect? Define it in your own words.
b) Where is it noticed most? Why?
c) Where is it noticed least? Why?
4. a) What prevailing winds did explorers take advantage of when travelling from
Europe to North America?
b) Which prevailing winds helped them return to Europe?
5. What are the 2 causes of prevailing winds?
6. What affects prevailing winds? How?
7. What is the saying to help you remember how jet streams change with turning
seasons?
Making Connections
1. What does the Coriolis Effect have to do with prevailing winds?
2. How does the Coriolis Effect affect pilots’ flight plans from one destination to
another?
3. Why is it not surprising to see deserts like the Gobi in Asia and the Sahara in Africa
at 30 N latitude given that prevailing winds help to distribute solar  from the
equator to colder parts of the world?