Wind
Wind
The wind blows because air has weight. Cold air weights more than warm air, so the pressure of cold air is greater.
When the sun warms the air, the air expands, gets lighter, and rises. Cooler, heavier air blows to where the warmer
and lighter air was, or in other words, wind usually blows from areas of high air pressure to areas of low pressure.
If the high pressure area is very close to the low pressure area, or if the pressure difference (or temperature difference)
is very great, the wind can blow very fast. Although wind blows from areas of high pressure to areas of low pressure,
it doesn't blow in a straight line. That's because the earth is rotating. In the northern hemisphere, the spin of the earth
causes winds to curve to the right. (To the left in the southern hemisphere) This is called the Coriolis force. So in the
northern hemisphere, winds blow clockwise around an area of high pressure and counter-clockwise around low pressure.
You can measure wind with a Anemometer
Wind vane / Anemometer
The use of simple instruments to indicate the direction of wind is very old practice. However, the measurement of its force and speed is a much more recent
accomplishment. The first record of the wind vane was first done about 300 years ago, but the first practical use of this instrument took place in the last half
of the 1800s. Anemometer (Greek anemos, "wind"; metron, "measure"), an instrument that measures wind speed. The most common kind of anemometer
consists of three or four cups attached to short rods that are connected at right angles to a vertical shaft. As the wind blows, it pushes the cups, which turn the
shaft. The number of turns per minute is translated into wind speed by a system of gears similar to the speedometer of an automobile. Wind velocity is also
measured by the pressure of the air blowing into a Pitot tube (an L-shaped tube, one end open toward the flow of air and the other end connected to a
pressure-measuring device), and electrically by the cooling effect of the wind on a heated wire, which causes the electric resistance of the wire to change.
An anemometer in which surface is held normal, or nearly normal, to the wind is theoretically simple but more difficult in practice.
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| 0 | Calm | Calma | 0 |
| 1 | Light Air | Ventolina | 2 |
| 2 | Light Breeze | Flojito | 5 |
| 3 | Gentle Breeze | Flojo | 10 |
| 4 | Moderate Breeze | Bonancible | 16 |
| 5 | Fresh Breeze | Fresquito | 20 |
| 6 | Strong Breeze | Fresco | 25 |
| 7 | Moderate Gale | Frescachón | 30 |
| 8 | Fresh Gale | Temporal | 35 |
| 9 | Strong Gale | Temporal Fuerte | 45 |
| 10 | Whole Gale | Temporal Duro | 50 |
| 11 | Storm | Temporal Muy Duro | 60 |
| 12 | Hurricane | Temporal Huracanado | 70 |
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| 0 | Calm | Calma | 0 |
| 1 | Rippled | Rizada | 0 - 0.25 |
| 2 | Smooth | Marejadilla | 0.25 - 0.50 |
| 3 | Slight | Marejada | 0.50 - 1.25 |
| 4 | Moderate | Fuerte Marejada | 1.25 - 2.50 |
| 5 | Rough | Gruesa | 2.50 - 4.00 |
| 6 | Very Rough | Muy Gruesa | 4.00 - 6.00 |
| 7 | High | Arbolada | 6.00 - 9.00 |
| 8 | Very High | Montañosa | 9.00 - 14.00 |
| 9 | Phenomenal | Enorme | More then 14 metres |
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