Wind Speed Converter: m/s, km/h, mph, Knots, Beaufort

The Beaufort scale is a 13-level classification (Force 0 to Force 12) that links wind speed ranges to observable effects on land and sea. It was devised in 1805 by Admiral Sir Francis Beaufort of the Royal Navy as a practical means of estimating wind without instruments. Force 0 is calm (less than 0.5 m/s), and Force 12 is hurricane force (32.7 m/s or more). The WMO adopted the scale internationally in 1947. It remains widely used in marine and aviation weather reports alongside numerical wind speed values.

Miles per hour (mph) measures distance in statute miles (1,609.344 metres). A knot measures one nautical mile per hour, where a nautical mile is 1,852 metres. Therefore 1 knot equals approximately 1.15078 mph, or 1.852 km/h. Aviation and maritime industries use knots because nautical miles relate directly to degrees of latitude, simplifying navigation calculations. Weather services in the United States use mph for public forecasts and knots for aviation and marine forecasts.

The Beaufort scale classifies Force 12 as hurricane force, with sustained winds of 64 knots (73 mph or 119 km/h) or more. The Saffir-Simpson Hurricane Wind Scale further classifies tropical cyclones: a Category 1 hurricane has sustained winds of 64-82 knots, Category 2 is 83-95 knots, Category 3 is 96-112 knots, Category 4 is 113-136 knots, and Category 5 exceeds 137 knots (157 mph). These definitions come from NOAA and the National Hurricane Center.

Wind speed is most commonly measured with an anemometer. Cup anemometers use rotating cups whose speed is proportional to wind speed. Ultrasonic anemometers measure the time of flight of sound pulses between transducers. Doppler radar detects frequency shifts in reflected radio waves to measure wind remotely. Wind lidar uses laser light. Officially reported wind speeds from weather stations are typically 10-minute averages at a height of 10 metres above open terrain, as standardised by the WMO.

The Saffir-Simpson Hurricane Wind Scale (SSHWS) classifies tropical cyclones into five categories based on sustained wind speed. Category 1 (64-82 kt): very dangerous winds causing some damage. Category 2 (83-95 kt): extremely dangerous winds causing extensive damage. Category 3 (96-112 kt): devastating damage. Category 4 (113-136 kt): catastrophic damage. Category 5 (137+ kt): catastrophic damage with most framed homes destroyed. The scale is published and maintained by the US National Hurricane Center (NHC), which is part of NOAA.