which type of rains are most powerful?
Could you please elaborate?
Rainfall depends on several variables - i.e. type of weather system (e.g. cumulonimbus clouds (very localized), or very large weather systems such as hurricanes/typhoons), relative humidity, temperature, pressure, and variations in these properties.
A rainfall or 1 - 2 inches (2-5 cm) in 1 hr may cause limited flooding, while in a 24 hour period would not be severe. Even with low rainfall amounts like these, persistent rainfall such as 4 or more days of rain can lead to flooding once the ground is saturated with moisture.
On the other hand, I have been in several situations with 10-12 inches (25-30 cm) of rain in 24 hrs and one period with approximately 20 inches (50 cm) of rain in two days. In these cases, substantial flooding over a wide area was the result.
With heavy rains, there is often wind, and some times there are downdrafts (downwinds) or microbursts with wind speeds of 10's of mph (km/h). The wind can be damaging above 40mph (64 km/h). I have been near the ocean where the wind blew the rain at an angle of something like 20-30° from horizontal. In that case, I could not see more than a few feet (2-3 m) in front of my face.
Tornados are associated with storm conditions that cause locally heavy rain.
Try this link - WW2010 (the weather world 2010 project), which was developed by the Department of Atmospheric Sciences (DAS) at the University of Illinois Urbana-Champaign (UIUC)
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