1. Winds

2. What is Wind?
The horizontal movement of air from High pressure to Low pressure.
HL
Air moving up or down (vertical) is called a current

3. What causes wind?
diferences in
pressure
H= High
L= Low

4. Pressure is caused by the characteristics of the air
X X X X X
X X X
X X X X
Molecules move faster and are
farther apart.
Warmer Air
Less Dense
Molecules are close together and move slowly.
X X X X X X X X X X
X X X X X X X X X X
X X X X X X X X X
Cooler Air
More Dense

5. Warm Air Rises Cool Air Sinks
Cool Air Sinking
Warm Air Rising
Warm Air Rising

6. Convection Currents
Cool Air Sinking
Cool Air Sinking
Warm Air Rising

7. High Pressure H AHHHH! High Pressure Ok, High Pressure is
Dense (heavy)
Cool
Creates Clear Skies

8. Low Pressure Whew! Low Pressure L Ok, Low Pressure is
Less Dense (heavy)
Warmer
Brings Lousy Weather
Whew!
Low Pressure L

9. High Pressure = Happy Weather H
Low Pressure = Lousy Weather L

10. Wind blows from areas of
to areas of
high
pressure
low
pressure

11. Correctly draw the direction of wind flow
on your paper

12. Winds Blow from HIGH to LOW

13. counterclockwise wind direction counterclockwise wind direction
low pressure
high pressure
warm or cold air
air rising or sinking
clouds or no clouds
clockwise or
counterclockwise wind direction
winds toward or
away from the center
low pressure
high pressure
warm or cold air
air rising or sinking
clouds or no clouds
clockwise or
counterclockwise wind direction
winds toward or
away from the center
warm
cold
rising
sinking
clouds
no clouds
counter clockwise
clockwise
toward
away

16. This is because the air is Therefore, clouds CANNOT form.
In a high pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds CANNOT form.

17. This is because the air is
In a low pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds are
LIKELY to form.

22. There Are Two Kinds of Winds: Global and Local
Global Winds are Winds that blow over long distances around the Earth.
Local Winds are winds that blow a short distance.

23. Global Winds

24. Why Do Different Parts of the Earth Have Different Temperatures?
North Pole
Equator
South Pole
Thus, radiation is more intense near the equator compared to the poles.
For this reason, it’s warmer near the equator than at the poles.

25. Global Thermal Temperatures

26. Air Rises at the Equator
Air at the Equator is warm.
Warm air rises.
The Equator is a Low Pressure area.
Warm Air Rises

27. What Happens to Rising Air at the Equator?
At the Equator, air rises;
As the air moves upward, it cools,
The air begins to turn to move downward.
Cold air sinks at the 30o zone.
Cool Air Sinks

28. High Pressure to Low Pressure
Winds blow from
High Pressure to Low Pressure
Low Pressure
HIGH PRESSURE
Low Pressure
HIGH PRESSURE
Low Pressure
HIGH PRESSURE

29. Let’s Label High Pressure 90°N Low Pressure 60 °N High Pressure 30°N
High Pressure 30°S
Low Pressure 60°S
High Pressure 90°S

30. How are winds named?
The direction
from which
they come

31. Names of Winds
IMPORTANT: Winds are named from the direction they come.
North winds comes from the north; south winds come from the south.
Southeast winds come from the southeast and blow northwest;
Northeast winds come from the northeast and blow to the southwest.

32. Let’s Label Easterlies
Polar Easterlies
Trade Winds
Trade Winds
Polar Easterlies

33. Trade Winds The TRADE WINDS are the winds blowing towards the equator.
These winds are Easterlies, blowing from the east.
South of the equator, the winds blow from the southeast
North of the equator, the winds blow from the northeast.
They were named because traders from Europe sailed in these zones on their way to the new world.

34. Let’s Label Westerlies
Prevailing Westerlies
Prevailing Westerlies

35. Inman is Located in the Westerly Wind Belt

36. Why Don’t The Winds Blow in Straight Lines?
Cold air from both the South Pole and North Pole blows towards the 60o zone
But the air doesn’t flow in a straight line

37. Coriolis Effect
Since the earth rotates, winds do not blow directly from north to south or south to north.
Winds curve
They curve because the earth rotates or spins on its axis.
The Coriolis Effect is the curving of winds due to the earth’s rotation.

38. The ball is going straight, but it looks like it is curving.

39. Global Wind Animation

40. Christopher Columbus
Columbus used both the Easterlies and Westerlies to go to and from Spain.

41. Columbus’s Route to and back
Trade Winds
Westerlies
To the New World from Spain, Columbus sailed in the Trade Wind Zone.
From the New World and back to Spain, Columbus sailed in the Westerlies zone.

42. Zones of NO WIND Doldrums At the equator, which
is 0o latitude, there is
a windless zone called
the Doldrums.
Horse Latitudes
At 30o N and 30o S,
there is a windless
zone called the
Horse Latitudes.

43. Horse Latitudes And The Doldrums Westerlies Horse Latitudes
Polar Easterlies
Horse Latitudes
And
The Doldrums
Westerlies
Horse Latitudes
Trade Winds
Doldrums
Trade Winds
Horse Latitudes
Westerlies
Polar Easterlies

44. Doldrums
Since the Trade Winds blow from both the North and South, a calm zone occurs.
This zone is called the “DOLDRUMS.”
In this zone, there are no winds. Ships often got stalled for long periods because they needed wind to blow their sails.

45. Horse Latitudes
The Horse Latitudes are zones of calm winds at the 30o Latitude Lines.
The term horse latitudes originates from the days when Spanish sailing vessels transported horses to the West Indies. Since there was no wind, the sail ships that entered this zone, would get stuck for weeks.
Since water and food shortages occurred, the crews found it necessary to throw their horses overboard.

46. 30o North and South Latitude
Sinking air means no clouds or rain.
Along this latitude, (between 15o to 35o) many of the major deserts are found
This is an area of high pressure.
Air from the Equator and from the 60o Latitudes cool and descend at the 30o Latitude. H H

47. Local Winds
Winds that blow short distances and in any direction (depending on pressure)
Remember, winds always blow from areas of high pressure to low pressure.

51. EXIT PASS WINDS BLOW FROM AREAS OF ______TO AREAS OF ______.
DURING THE DAY WHICH HEATS FASTER? LAND OR WATER
DURING THE NIGHT WHICH COOLS DOWN THE FASTEST? LAND OR WATER