Kiteboarding Magazine

Kristin
2009-11-02 13:09:05 | 4337 views | 1 Comments

Even though weather reports give you predictions and current wind conditions, observing the conditions firsthand is tremendously useful. In this article you’ll learn a few things that will help you forecast and read the weather, wherever you may be.

Air is set in motion when Mother Nature tries to equalize pressure by moving regions of high pressure to regions of low pressure. Basically, when pressures change, winds blow. You can measure wind by its speed, direction and the change factor.

WATER TEXTURE
When winds blow, they affect the water’s surface. Here are some facts that will help predict how smooth or choppy your ride might be.
• Whitecaps start forming at around 12 knots. The larger and more frequent they are, the stronger the wind.
• Consistent water textures indicate stable winds.
• Darker patches of water often look like a cloud’s shadow that’s moving across the water. Typically, this indicates a strong gust is coming.
• Flatter, glasslike water indicates little air movement at the water’s surface. If you notice glassy spots forming, the winds are decreasing and may stop completely.
• Often, you can see the wind “line.” In some areas, winds may be light near shore but stronger out at sea. On the beach, you can actually see the line where whitecaps will start, which signifies stronger winds approaching. Wind lines can move fast (especially squalls), so be cautious.

WIND TURBULENCE
If the world was flat and smooth, there would be little wind variation from place to place. But by adding topography (hills, valleys, trees, buildings, islands, etc.), a highly variable wind regime exists. Known as surface friction, objects in the path of wind flow affect all three wind traits (speed, direction, change).

Rough surfaces, such as areas with trees and buildings, will produce more friction and turbulence than smooth surfaces, such as lakes or open cropland. Obstructions can drastically reduce wind quality by adding nasty turbulence. Or, there may even be a wind “shadow” where an object impedes the wind flow.

While buildings, hills, valleys, trees and mountains typically create unstable air, each geographical feature uniquely influences the flow of wind. Certain conditions, such as that of valleys – which tend to funnel winds into tighter spaces – can actually accelerate the wind.

Through reading water texture and understanding turbulence, you’re well on your way to being a wind guru. However, you should also know about the dangers of thunderstorms, squalls, etc., so it is a good idea to continue your education.

THE LAW OF TURBULENCE
When wind flows over an object, it becomes turbulent for seven times the object’s height downwind and three times the object’s height upwind and sidewind.