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Wind speed on the Beaufort scale is based on the empirical relationship: [6] v = 0.836 B 3/2 m/s; v = 1.625 B 3/2 knots (=) where v is the equivalent wind speed at 10 metres above the sea surface and B is Beaufort scale number.
These warnings use a 1-minute sustained wind speed and can be compared to the Saffir–Simpson hurricane wind scale, however, regardless of intensity in this basin the JTWC labels all systems as tropical cyclones with TC numbers (plus any parenthesized names or placeholders, like typhoons and North Indian Ocean cyclones above). [18]
The old scale lists an F5 tornado as wind speeds of 261–318 mph (420–512 km/h), while the new scale lists an EF5 as a tornado with winds above 200 mph (322 km/h), found to be sufficient to cause the damage previously ascribed to the F5 range of wind speeds.
In 2012, the NHC extended the wind speed range for Category 4 by 1 mph in both directions, to 130–156 mph, with corresponding changes in the other units (113–136 kn, 209–251 km/h), instead of 131–155 mph (114–135 kn, 210–249 km/h).
Most pressure-wind models are in the form of: [4] = Where v m is the maximum wind, Δp is the change in pressure from an external point to the center. a and x are constants. [4] Ted Fujita was the first to modify the exponent; before then, it mostly stood at 0.5. [4]
For the intensity scale, PAGASA lowered the threshold wind speed for classifying super typhoons from 220 km/h to 185 km/h and defined a super typhoon as an extreme tropical cyclone with 10-minute maximum sustained winds reaching 185 km/h or greater (the range of wind speed for typhoon category is consequently adjusted to 118–184 km/h).
For zero-second wind speed measurements, it is assumed to be an instantaneous wind speed measurement. [ 4 ] [ 3 ] This can only be used if it was 10 Hz or higher sample rate. [ 4 ] [ 3 ] [ 6 ]
An anemometer is commonly used to measure wind speed. Global distribution of wind speed at 10m above ground averaged over the years 1981–2010 from the CHELSA-BIOCLIM+ data set [1] In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in ...