GEOG 2HI3 Lecture Notes - Lecture 1: Pressure-Gradient Force, Weather Vane, Coriolis Force
Document Summary
Wind is horizontal motion of air across earth"s surface and it"s two primary characteristics are speed and direction. Anemometer: used to measure wind speed (from greek origin anemo which means wind knots) Measure in km/hr, metres/hr or miles/hr or knots (knotical mile/hour) A wind vane is used to determine wind direction and is taken at least 33 feet above the ground in order to reduce the effects of local topography on wind direction. Closer to surface of the earth there is greater volume/accumulation of molecules of gases (n, co2, o2, etc. ) This increases the amount of pressure and as you move upward pressure decreases with altitude. Wind moves from a region of higher atmospheric pressure to lower. The speed and path of the wind is influences by the balance of three forces: the pressure gradient force, coriolis force, and frictional force. Pressure gradient force is caused by differences in atmospheric pressure from one location to another.
