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 ...
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 ...
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 >...
22
votes
2answers
5k views

Is there an upper bound to the amount of rain that can fall in an hour?

The record for most rainfall in a single hour is 12 inches (30.5 cm), set in Holt, Missouri, in 1947. What is the maximum amount of rainfall that could theoretically occur in an hour?
16
votes
8answers
5k views

Ways to make a “How hard is it raining?” detector for personal use?

Is there a consensus on the "heaviness" of rain? and Relationship between Probability of Precipitation and Predicted Amount of Rain remind me of a gedankenexperiment of mine. I like to ...
14
votes
3answers
19k views

If it rains harder, does it mean the rain's duration will be shorter?

If it rains real hard, is there a chance the rain's duration will be shorter? I think the if the rain in the clouds disperses with such force the rain will be over faster than if it was just a light ...
13
votes
1answer
912 views

Do forests affect local rainfall and climate significantly?

I know that forests can change the local temperature, but what about rainfall?. Do forests affect rainfall in their region? I have read that if a forest is very big, it can cause minor changes to ...
10
votes
1answer
1k views

How does evapotranspiration affect rainfall?

Evapotranspiration is when a plant evaporates water off the surface of its leaves in order to move water throughout its system with cohesive and adheisiveforces. My question is how will a sudden ...
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. (...
9
votes
6answers
545 views

Any historical examples of destructive climate warming?

Summation: Local cooling climate changes, since the last ice age seem relatively common and all seem to cause significant harm to human population. But I can't find instances of the reverse, warming ...
9
votes
1answer
868 views

Can earthquakes affect the atmosphere?

Recently an earthquake of magnitude 6.9 shook the northeastern region of India, where I live. After the earthquake, the climate has changed dramatically resulting in excessive hail showers, ...
8
votes
2answers
255 views

Could a reported rainfall pH of 3.1 actually be realistic?

In this Chemistry question Is there any reason to fear personal exposure to rain with a pH of 3.1? I haven't gotten any answer, but there was some discussion about the reality of the measurement. So ...
8
votes
2answers
228 views

TRMM rainfall measurement for synoptic systems

I have gone through the website of TRMM that explains how the TRMM satellite gather precipitation data- http://pmm.nasa.gov/node/158. During the Indian Summer Monsoon (ISM), we have synoptic systems ...
8
votes
2answers
1k views

How accurate is a tipping-bucket rain gauge?

My question is simple - how accurate is a tipping-bucket rain gauge? I have read about what causes the errors (wind, bucket mechanics for extreme events, ...) and I know the accuracy is strictly ...
8
votes
2answers
195 views

How can there be a hot summer with rain and no thunderstorms and lightning?

This summer in the south of France we have had two hot months with 29 days over 30'C, while the average maximum is 26'C in July. Normally there are violent storms with lightening up to 20 times a ...
8
votes
1answer
2k views

Causes and concentration of red rain of Kerala

The red rain phenomenon in Kerala, India has been reported several times in history (1896, 2001, 2012). The color of the rain seems to be associated with the presence of airborne spores of the algae ...
7
votes
3answers
6k views

How do rivers last so long in dry weather?

I got caught in a downpour while climbing a mountain and was amazed to see, as I climbed down, the tiny trickles of water combine to form mini-streams, the dry rocks I had climbed up now hosted ...
7
votes
2answers
760 views

Why is northern Australia unsuitable for agriculture?

Northern Australia receives substantial rainfall, but its population is minimal. For instance the Kimberley region in the state of Western Australia gets more than 20 in. of rainfall per year, but ...
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 ...
7
votes
1answer
300 views

Why is Venezuela so dry?

I'm trying to understand why the summer (January) precipitations in Venezuela are so low in the central and southern parts of the country as well as in eastern Colombia. The most plausible explanation ...
6
votes
1answer
634 views

The sun sometimes appears pure white after rainfall, how can this be explained?

I've noticed on multiple occasions, that after heavy rainfall, the sun appears a pure glistening white, even if it's already standing low in the sky. I can't discount psycho-visual effects as an ...
6
votes
3answers
102 views

Accepting/refusing high rainfall measurement

I have a series of records of annual maximum daily rainfall for a station for about 80 years (1935-2014). Only one value is very high compared with the others, but in this year, the other close rain-...
6
votes
1answer
156 views

Do Siberia and Canada have a rasputitsa?

The rasputitsa is a muddy season that happens twice per year in West Russia, Ukraine, and Belarus. It happens in mid-October to late November due to rains, and mid-March to late April due to thaws (...
6
votes
1answer
89 views

Is there a method to determine the point rainfall intensity for small catchments?

I need to design a weir for a small earth dam in an arid area with a small (smaller than 200 ha), fairly flat catchment area in southern Africa. The idea behind the dam is to collect not more than 10 ...
6
votes
1answer
527 views

Why is there no desert in Southeast China?

Arabia, Sahara and Southeast China and India all are on the tropic of Cancer yet Southeast China and India are not deserts. I know that India is not a desert because of monsoon wind which causes heavy ...
6
votes
1answer
138 views

Does a hurricane classification exists where estimated rainfall is taken into account?

Hurricanes are classified with the Saffir–Simpson hurricane wind scale. However an extreme amount of rainfall can cause a disaster although the windspeeds are not extreme. Is there some sort of ...
5
votes
2answers
126 views

How to determine constant $C$ in $p(x) = Cx^{-D}$?

Given a distribution obeying the power-law (fractal) relation, such as the cumulative distribution function $L_{cf}(> X) = CR^{-D}$, if $X$ is given, how does one find the constant $C$ from a given ...
5
votes
1answer
127 views

Why is thunder and lightning rare, even though it rains frequently?

Why in some places (for example Dublin, Ireland) the thunder and lightning is such a rare thing even though it rains so frequently?
5
votes
2answers
15k views

How much time does water takes to reach to the ground?

I want to understand the phenomena where water droplets after precipitation reaches to the ground. How much time does it take to become ground water or in other words how much time is taken by water ...
5
votes
1answer
207 views

How does high rate of evapo-transpiration contribute to the ineffectiveness of rainfall?

If evapo-transpiration is high then more water vapor is taken up to the atmosphere and more condensation takes place resulting in more rainfall. But in the book The Environment of Pakistan by Huma Naz ...
5
votes
1answer
228 views

Need help understanding rain rate formulas from drop sizes

I have come across different formulas by which the rain rate [mm/s] or [mm/h] can be computed from the drop size distribution. I'm somehow unable to convert the different formulas into each other. It ...
5
votes
1answer
71 views
+100

What are typical ranges of rainfall drop sizes, speeds, and areal or volume densities?

I'd like to look into the possibility of using a Raspberry Pi and the PiCam module to detect rain, and to try to make some measurements of droplet size and rate. This could be done using an LED flash ...
5
votes
0answers
89 views

Using salinity to predict rainfall

Recently, a new method has been proposed by Ray Schmitt (WHOI) and collaborators to use salinity patterns in the ocean to predict weather events (more specifically, rainfall) at scales from weeks to ...
4
votes
3answers
147 views

Why are rain weather predictions (apparently) so unreliable still in the year 2021?

A year or so ago, I finally implemented a little mechanism which, every five minutes, fetches weather data from SMHI (Swedish official organization, having kept track of temperatures and stuff since ...
4
votes
1answer
126 views

Where can I find the record for the heaviest single-day rainfall ever recorded on any date at a specific location?

I need to find out the largest amount of rainfall ever recorded in Atlanta, Georgia, USA. Where could I find this record?
4
votes
4answers
800 views

How can we calculate the total water mass that falls during a flood?

I would like to know how to calculate how much water fell on California during, for instance, the mid-February 2017 flood. I know how to look up the total rainfall at a specific weather station. And,...
4
votes
1answer
130 views

How effective is seeding rainclouds? What are the indications for initiating seeding?

I've heard that dry ice, iodides have been used as seeding agents to induce rainfall. Is this technique really being used widely? What are the prerequisites for initiating seeding? Is it as bounteous ...
4
votes
1answer
102 views

Could a waterfall lashing onto a road lead to a landslide?

Here is a video of a waterfall lashing on to a mountain road, with vehicles driving under it. https://youtu.be/cHaguj--YBc There appears to be a big hole carved out right next to the road, possibly ...
4
votes
0answers
40 views

Free historical weather data API

Where can I find a free Python API that provides historical weather data (temperature, rainfall)? I'd need data of an Italian city, at least with hourly granularity.
4
votes
0answers
72 views

Roughly what proportion of a cloud does 'rain out'?

What proportion of the water in a cloud will 'rain out'? Or, comparing the cloud before and after it has rained, what proportion of the water is left afterwards? I really have no idea so am just ...
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 &...
3
votes
1answer
235 views

Extreme rainfall events

Extreme rainfall events have different intensities at different places depending on the availability of water to precipitate. Can anyone explain how do we define/determine extreme rainfall events in a ...
3
votes
2answers
41 views

Find optimum number and location of rain gauges

Is there any recommended method for finding the optimum number and location of rain gauges over a region based on the data from existing rain gauges. There is one Isohyetal method that does not give ...
3
votes
1answer
277 views

What statistical methods are best for analyzing long-term rainfall data?

What statistical tools are best analysing rainfall data (overall trends, decadal trends, intensity distribution, extremes, etc.)?
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 ...
3
votes
5answers
1k views

How is Doppler radar used in rain prediction?

How is Doppler radar used in rain prediction?
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
0answers
139 views

Desert greening - Do we have long term (several decades) data on precipitation around the Sahara?

This article of desert greening states that some areas around the Sahara have seen increased plant growth in recent decades, caused by global warming. The causal chain would be warmer air can hold ...
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?
2
votes
1answer
6k views

How to identify low or high pressure area

If rain is due to the flow of humid air from a high pressure area to a low pressure area, without the use of devices, technology or mass media is it possible to detect regions of high or low ...