Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
Lesson Objectives:
At the end of this lesson students will be able to:
1. Define the coriolis effect.
2. Explain why winds turn to the right in the northern hemisphere and to the left in the southern hemisphere.
3. List the names and locations of the six global wind patterns.
4. Explain why the global wind patterns blow the way they do.
Prevailing Winds
­ Prevailing winds are winds that affect a large area and consistently blow in one general direction.
­The driving force behind the prevailing winds, like all wind, is the energy from the sun.
­Coriolis effect which is the apparent change in direction of an object in a rotating system, plays a major part in the prevailing winds.
1
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
Coriolis Effect
Coriolis Effect is the apparent deflection of a body in motion with respect to the earth, as seen by an observer on the earth. It is caused by the rotation of the earth and appears as a deflection to the right in the Northern Hemisphere and a deflection to the left in the Southern Hemisphere.
Watch
this
video!
North
Pole
SUN
The Earth spins counter­clockwise as viewed from above the North Pole
2
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
North
Pole
Cold air blowing down on the north pole flows southward over the earth, but the earth spins counter clockwise under it. This causes an apparent turning of the wind toward the right.
May 27, 2016
SUN
Global Wind Circulation Watch
this
video!
3
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
Equator
Equator
4
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
Equator
Equator
0°
5
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
­ As air is heated at the equator it rises high into the atmosphere. It has to be replaced at the surface by air that blows in from north and south of the equator. As the air rushes in from North and South it turns due to the coriolis effect. In the northern hemisphere air (and water) turns toward the right. In the southern hemisphere it turns to the left. This gives us the NE trade winds above the equator and the SE trade winds below the equator. Cold air descends upon the poles and flows toward the equator. However once again the coriolis effect causes the wind to turn, since the earth turns under the air, giving us the polar easterlies. The middle areas from 30° to 60° are affected by advection due to a high pressure belt near 30° and a low pressure belt at around 60°. As the air flows toward the poles in this belt it is moving faster than the earth under neath it which causes it to turn toward the east (come from the west). These winds are called the mid­latitude westerlies.
Polar Easterlies
60° N
Mid­Latitude Westerlies
30° N
NE Trade Winds
Equator
SE Trade Winds
30° S
Mid­Latitude Westerlies
60° S
Polar Easterlies
6
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
Prevailing Winds:
May 27, 2016
High Pressure
Polar Easterlies
60° N
Low Pressure
Mid­Latitude Westerlies
30° N
High Pressure
NE Trade Winds
Equator
Low Pressure
SE Trade Winds
High Pressure
30° S
Mid­Latitude Westerlies
Low Pressure
60° S
Polar Easterlies
High Pressure
Watch
this
video!
HW/SW: Read pp. 516 ­ 519 in your text
Complete questions 1 ­ 7 p. 519
7
Weather_3 ­Coriolis_PrevailingWinds_2015.notebook
May 27, 2016
Equator
60
50
12
40
140
30
150
20
160
10
0
130
170
180
8
Attachments
Global Atmospheric Circulation.mp4