Introduction
The Great Lakes — individually and collectively — play a significant role in the region’s weather. This is especially evident in the spring and early summer when cold lake waters promote the development of fog, suppress temperatures along the shore, and diminish the potential for strong thunderstorms offshore. One phenomenon of particular interest to sailors is the significant impact a relatively cold lake has on the wind well into the summer months.
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Tag Archives: Wind Forecasting
Forces Governing The Wind
Pressure Gradient Force
The speed and direction of the wind is governed by three forces; the pressure gradient force (PGF), the Coriolis Force and friction. PGF is the force produced by differences in barometric pressure between two locations and is responsible for the flow of air from an area of high pressure to an area of low pressure.
Flow of air produced by the pressure gradient force.
The diagram above shows an idealized surface weather map containing a 1030+ mb high pressure system and a 1002+ mb low pressure system. In the absence of the Coriolis Force and friction, the wind flows directly from the center of the high to the center of the low. The speed of this flow is dictated by the magnitude of the change in barometric pressure and the distance between the centers of the high and the low.
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