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The heard static is a combination of white noise (cumulative of distant thunderstorms) and impulse noise (from relatively nearby thunderstorms, if any). The power-sum varies with seasons and nearness of thunderstorm centers. It can be seen as random speckles on an old analog TV set dialed to an empty channel.
Thunder is the sound caused by and after lightning. [ 1 ] [ 2 ] [ 3 ] Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning produces rapid expansion of the air in the path of a lightning bolt . [ 4 ]
In Canada, a rainfall rate greater than 50 millimetres (2 in) in one hour, or 75 millimetres (3 in) in three hours, is also used to indicate severe thunderstorms. [38] Severe thunderstorms can occur from any type of storm cell.
[10] Severe is defined as hail 1 to 2 inches (25 to 51 mm) diameter, winds 58 to 75 miles per hour (93 to 121 km/h), or a tornado. [11] Significant severe is defined as hail 2 inches (51 mm) in diameter or larger, winds 75 mph (65 knots, 120 km/h) or more, or a tornado of strength EF2 or stronger. [1] [12]
Thunder is heard as a rolling, gradually dissipating rumble because the sound from different portions of a long stroke arrives at slightly different times. [99] Lightning at a sufficient distance may be seen and not heard; there is data that a lightning storm can be seen at over 160 km (100 miles) whereas the thunder travels about 32 km (20 miles).
Thundersnow, also known as a winter thunderstorm or a thundersnow storm, is a thunderstorm in which snow falls as the primary precipitation instead of rain. It is considered a rare phenomenon. [ 1 ] It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone .
Hail cannon in 2007 Hail cannons in 1901 Hail cannon in Banská Štiavnica Old Castle (Slovakia). Probably designed by Julius Sokol. A hail cannon is a shock wave generator claimed to disrupt the formation of hailstones in the atmosphere.
The scale of dBZ values can be seen along the bottom of the image. 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]