While wind speed and air pressure may seem to be unrelated properties of air, they are in fact one and the same property for all fluids, including air and water.

Wind is air pressure converted into movement of air. When air slows down, its pressure increases. The kinetic energy or momentum of a moving air mass is converted in static atmospheric pressure as the air mass slows down. This means that higher wind speeds will show lower air pressure readings. It is also the reason why tornadoes suck debris up their funnel and why airplanes have to be moving fast to lift their weight. Since wind speed will effect air pressure measurements, it is important to place pressure sensors in windless places.

Experience has shown that pressure compensation for wind speed built into anemometers does not provide the necessary accuracy and stability for meteorological measurements since anemometer reaction time (response time) is much slower than that of a pressure sensor. Placing pressure sensors in wind shielded places to avoid compensation is the only reliable way to measure air pressure.

Second important fact to know about air pressure observations is that the air pressure reported in weather reports and weather forecasts is not the air pressure measured by a weather station unless the weather station is located at sea level. So that meteorologists can directly compare air pressure readings from weather fronts, they must standardize the readings by converting the local measured pressure (also known as barometric pressure or gauge pressure) to sea-level equivalent air pressure (QNH) whose aeronautical code is Q. Once converted and standardized, the sea-level equivalent air pressures can be directly compared and a meteorologist can determine which weather front has higher or lower atmospheric pressure. This allows meteorologists to create weather forecast based on the observed weather station data.

• Mean Sea Level Pressure Calculator (Converter) – Advanced Formula - convert your weather station barometric (gauge) pressure into mean sea-level equivalent pressure (QNH) as used in weather forecasting, weather reports and aviation.