Wind
Wind is the movement of air caused by the uneven heating of the Earth by the sun. It does not have much substance. It is strong enough to carry sailing ships across the ocean and rip huge trees from the ground. It is the great equalizer of the atmosphere, transporting heat, moisture, pollutants, and dust great distances around the globe. Landforms, processes, and impacts of wind are called Aeolian landforms, such as sand dunes and Loess deposits, which are deposits of silt. Differences in atmospheric pressure generate winds. At the Equator, the sun warms the water and land more than it does the rest of the globe. Warm equatorial air rises higher into the atmosphere and migrates toward the poles. This is a low-pressure system. At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air. This is a high-pressure system. Winds generally blow from high-pressure areas to low-pressure areas. The boundary between these two areas is called a front. The complex relationships between fronts cause different types of wind and weather patterns.
Wind rose, map diagram that summarizes information about the wind at a particular location over a specified time period. A wind rose was also, before the use of magnetic compasses, a guide on mariners’ charts to show the directions of the eight principal winds. The modern wind rose used by meteorologists gives the percentage of the time the wind blows from each direction during the observation period; it sometimes shows the strengths of these winds and the percentage of the time calm air or light winds are observed. This wind rose usually has eight radiating lines, whose lengths are proportional to wind frequency, and shows wind strength by the thickness of the lines or by feathers attached to them. The frequency of calm or nearly calm air is given as a number in the centre.
Table of Frequencies (%)
Direction
|
< 0.5 m/s
|
0.5-1 m/s
|
1-2 m/s
|
2-3 m/s
|
3-4 m/s
|
4-5 m/s
|
> 5 m/s
|
Total
|
N
|
0.09
|
0.37
|
1.42
|
0.78
|
0.00
|
0.00
|
0.00
|
2.66
|
NNE
|
0.32
|
0.50
|
1.51
|
0.73
|
0.00
|
0.00
|
0.00
|
3.06
|
NE
|
0.09
|
0.50
|
2.01
|
1.64
|
0.18
|
0.00
|
0.00
|
4.42
|
ENE
|
0.00
|
0.50
|
2.42
|
3.97
|
2.05
|
0.14
|
0.00
|
9.08
|
E
|
0.18
|
0.50
|
2.51
|
2.83
|
0.91
|
0.23
|
0.00
|
7.16
|
ESE
|
0.27
|
0.41
|
1.74
|
0.96
|
0.41
|
0.09
|
0.05
|
3.93
|
SE
|
0.14
|
0.41
|
1.42
|
0.59
|
0.37
|
0.05
|
0.00
|
2.98
|
SSE
|
0.05
|
0.32
|
0.68
|
0.68
|
0.27
|
0.00
|
0.00
|
2.00
|
S
|
0.23
|
0.23
|
1.05
|
0.55
|
0.05
|
0.00
|
0.05
|
2.16
|
SSW
|
0.05
|
0.32
|
0.91
|
0.68
|
0.23
|
0.05
|
0.05
|
2.29
|
SW
|
0.14
|
0.37
|
1.74
|
1.42
|
0.64
|
0.05
|
0.00
|
4.36
|
WSW
|
0.18
|
0.55
|
1.37
|
2.65
|
2.19
|
0.64
|
0.18
|
7.76
|
W
|
0.00
|
0.41
|
1.42
|
2.56
|
2.33
|
1.60
|
4.02
|
12.34
|
WNW
|
0.14
|
0.27
|
1.51
|
3.61
|
4.06
|
3.70
|
5.57
|
18.86
|
NW
|
0.05
|
0.41
|
1.00
|
2.83
|
4.43
|
2.33
|
1.10
|
12.15
|
NNW
|
0.09
|
0.27
|
1.14
|
2.01
|
1.10
|
0.18
|
0.05
|
4.84
|
Total
|
2.02
|
6.34
|
23.85
|
28.49
|
19.22
|
9.06
|
11.07
|
100
|