"Micro Cooling Fan" is the plane perpendicular to the direction of gas flow by the wind pressure. Pressure (wind pressure) due to the blocking of the building, so that the ambient air is blocked, the dynamic pressure drop, and side and back of the static pressure increase local vortices generate static pressure drop and distant disturbed airflow, this kind of "Micro Cooling Fan"static collectively referred to as the raising and lowering air pressure, the air heavy and gravitational acceleration with latitude and altitude change. In general, ρ than in the plains on the small plateau, that same wind speed at the same temperature, which produces a "Micro Cooling Fan" little pressure on the plateau than in the plains.