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The scale of dBZ values can be seen along the bottom of the image. Decibel relative to Z, or dBZ, is a logarithmic dimensionless technical unit used in radar. It is mostly used in weather radar, to compare the equivalent reflectivity factor (Z) of a remote object (in mm 6 per m 3) to the return of a droplet of rain with a diameter of 1 mm (1 mm 6 per m 3). [1]
So an intensity of 115 kn is rated Category 4, but the conversion to miles per hour (132.3 mph) would round down to 130 mph, making it appear to be a Category 3 storm. Likewise, an intensity of 135 kn (~155 mph, and thus Category 4) is 250.02 km/h, which, according to the definition used before the change would be Category 5.
Single-cell thunderstorms form in environments of low vertical wind shear and last only 20–30 minutes. Organized thunderstorms and thunderstorm clusters/lines can have longer life cycles as they form in environments of significant vertical wind shear, normally greater than 25 knots (13 m/s) in the lowest 6 kilometres (3.7 mi) of the ...
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Thunderstorms which show radar returns above 14 kilometres (8.7 mi) in height are associated with storms which have more than ten lightning flashes per minute. There is also a correlation between the total lightning rate and the size of the thunderstorm, its updraft velocity, and amount of graupel over land.
Around 1950, a good surface prognostic chart was considered to be one whose isobars were in the correct location. [19] By 1957, it was proposed when isobars or height lines at the 500 hectopascals (15 inHg) pressure level in the atmosphere were being verified, that the degree of persistence should be considered so as to avoid getting bad ...
While the summer of 2023 has been a season of smoke for parts of the northern United States, it has been a season with many thunderstorms for much of the Plains and Midwest.
The result is the nearly daily development of clouds that produce thunderstorms. For example, "Lightning Alley"—an area from Tampa to Orlando—experiences an extremely high density of lightning strikes. As of 2007, there were as many as 50 strikes per square mile (about 20 per km 2) per year.