Questions tagged [rainfall]

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97
votes
6answers
20k views

How can a storm drop 40 inches (1 metre) of rain?

Hurricane Harvey dumped more that 20 inches (500 mm) of rain over a large region, with 40+ (>1000 mm) in some spots... and much more expected. How is that possible? Does the atmosphere really hold ...
30
votes
2answers
53k views

At what humidity does it start to rain?

As far as I understand it is perfectly valid for air to have 100% humidity. At that point, all water can still exist in form of vapor, non-condensed. Does it immediately start to rain if humidity is >...
37
votes
10answers
78k views

What does a mm of rain mean?

Lots of people have explained it over many sites but I still can not confidently say that I know what it means when they say Hong Kong experienced 3mm of rainfall last Friday. Does it mean that 3mm ...
9
votes
2answers
2k views

Why do rivers sometimes travel down the opposite side of the mountains from where the rain happens?

My teacher explained that when wind coming from the ocean gets blocked by a mountain it makes rain on one side of the mountain, like in the image below. This rain leads to the creation of rivers. (...
3
votes
1answer
57 views

Relationship between Probability of Precipitation and Predicted Amount of Rain [duplicate]

If a popular website provides an hourly forecast, and it states at 12:00pm there will be a 20% chance of precipitation and 2.5 mm of rain... What does the "2.5 mm of rain" mean? (A) ... If ...
7
votes
3answers
554 views

Algorithmically Determining the Rainy Season

I have historical precipitation data for hundreds of cities around the world. I would like to algorithmically determine when the rainy season (if exists) is for each location. Are there any algorithms ...
3
votes
2answers
117 views

Why do clouds have areas of darkness instead of scattering light to produce a rainbow?

I suspect it has to do with the difference in size of a rain drop and that of the water particles in the cloud.
3
votes
2answers
148 views

Is there a consensus on the “heaviness” of rain?

As part of the home dashboard I am developing, I get information about incoming rain. It is given in mm/min. Is there a consensus on the precipitation rate that is called "light rain", or &...
2
votes
3answers
17k views

How does elevation affect the amount of rainfall received?

How does elevation affect the amount of rainfall received? Does elevation affect precipitation?
0
votes
2answers
102 views

Deserts and Humidity

How is that a general rule of thumb that less humidity equals more rain? Deserts don’t get much rain and humidity is also very low. Rainforests get a lot of rain when the humidity is very high so how ...
0
votes
1answer
96 views

Humidity and Rainfall

Usually the higher the humidity the more rainfall we get like in the summer here in Asheville, North Carolina we get a lot of showers and thunderstorms in the summer from the high humidity but I saw ...