Questions tagged [meteorology]

The study of how the earth's atmosphere works, including weather forecasting. Use this tag for questions about the earth's weather. When asking questions specifically about the atmosphere, also include the [atmosphere] tag.

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21
votes
3answers
42k views

How do I convert specific humidity to relative humidity?

How do I convert specific humidity to relative humidity? What variables are needed (e.g. air temperature, pressure, etc.)?
8
votes
1answer
126 views

Why does the Northern polar vortex usually have two centers?

From http://glossary.ametsoc.org/wiki/Polar_vortex polar vortex A planetary-scale mid- to high-latitude circumpolar cyclonic circulation, extending from the middle troposphere to the ...
11
votes
1answer
279 views

How can you explain this storm phenomenon?

It's been a while since this happened, so I don't have many details. About 3 years ago, we had a popup storm here in Louisville. It was completely unexpected and unpredicted. That's not the strange ...
3
votes
1answer
1k views

Why do some places have rain frequently? [closed]

There are some places on Earth which holds the record of being "The wettest place on Earth". On what factors these places differ from other normal places? An example of wettest place on Earth is ...
10
votes
1answer
96 views

North Indian ocean tropical cyclones

Why are tropical cyclones in the Bay of Bengal more frequent and stronger than those in the Arabian Sea?
6
votes
1answer
196 views

Am I observing orographic rainfall?

I don't know an awful lot about meteorology, so please bear with me. My wife (who has a Geography degree) told me that rain can be generated when moist air is pushed up the side of a mountain. This ...
10
votes
1answer
692 views

How could humans alter storm intensity or direction other than cloud seeding?

I am familiar with the concept of cloud seeding, where precipitation can be induced with aerosols, thereby altering storm intensity further downwind. Are there methods that could be used to ...
7
votes
0answers
429 views

Calculating Monthly Accumulation value of the Clearness Index KT

I have an hourly data file of a particular location which contains the following variables (extracted from the Meteonorm7.0 data base, for a typical one year of data): GlobHor (W/m2): Horizontal ...
18
votes
2answers
4k views

What are the applications of hydrostatic solvers vs non-hydrostatic solvers in numerical weather prediction?

In the atmospheric dynamics research community, many colleagues of mine happen to use atmospheric models that have non-hydrostatic equation solvers, e.g. the UK MetOffice model, and WRF-ARW: The ...
13
votes
1answer
155 views

Great Lakes - cookie cutter clouds

On 2014-07-10, in the afternoon, the GOES East satellite image in the visible showed a mass of cloud in central North America. However, in the middle, the Great Lakes stood out in a most extraordinary ...
8
votes
0answers
134 views

Relation of El Niño to Monsoons

Scientists are forecasting a weak to moderate El Niño event to emerge in the coming months, what causes this to happen? Once developed, how will the El Niño conditions effect progressive monsoon ...
19
votes
1answer
1k views

Why is there no middle ground between tornadoes and hurricanes?

A tornado has an effective area of destruction about the size of a city block. A hurricane spans several hundred kilometers. However, there doesn't seem to be a continuum between the two. Why are ...
9
votes
1answer
64 views

Is there a reliable way to identify regions with negatively-correlated winds?

When examining the potential for large-scale electricity grids, and when identifying the lowest-cost ways to generate clean electricity, a recurring theme is of spreading wind generation across a wide-...
12
votes
1answer
420 views

How is the Rossby Radius used to determine that synoptic weather systems are 1000-2000km across?

In one of his presentations, Sandy MacDonald (of NOAA and ESRL) talks about the Rossby Radius of Deformation in connection with the size of synoptic weather systems: he describes how it sets the ...
20
votes
1answer
744 views

What data does a skilled meteorologist look at to predict thunderstorms?

An uneducated layman like me would just look at CAPE numbers and make rough guesses on possible thunderstorms. In a related but non-duplicate question, vertical wind shear is discussed. If we are ...
10
votes
1answer
130 views

Is there a convenient place to get vertical wind shear info for my location?

Now that it's thunderstorm season here in New Hampshire, it would be nice to be able to find out what the vertical wind shear is like at the altitudes that affect thunderstorm formation, to guess ...
10
votes
1answer
869 views

What are Tetens coefficients?

Tetens coefficients appear in a few meteorological/climatological models that I've been looking at,for example APSIM: svp_A = 6.106 svp_B = 17.27 svp_C = 237.3 ...
9
votes
1answer
474 views

How can I downscale daily values of relative humidity?

I have a dataset (The ISIMIP interpolation of CMIP5 output) that contains daily values of the following variables: ...
10
votes
2answers
4k views

Is the urban heat island effect stronger during a particular season or part of the year?

It is known that cities tend to be warmer than the surrounding landscapes, and this is known as the "urban heat island effect". In the summer there is greater heat output from air conditioning ...
6
votes
1answer
4k views

Why is Sacramento so warm for its latitude?

http://en.wikipedia.org/wiki/Sacramento,_California It has high winter temperatures and high summer temperatures too.
7
votes
1answer
130 views

Does over-cropping large areas really change the amount of rainfall?

I heard that at one time the Sahara desert was cropped in wheat for the Roman Empire, and that cropping without adding back to the soil was what caused the desert to form. I also heard that this is ...
5
votes
1answer
2k views

If there's acid rain, is there such thing as acid snow?

If so, would the acid snow just be as damaging?
11
votes
2answers
348 views

Propagation of sound after lightning

In an area of frequent thunderstorms, I notice a 'crack or whoosh' sound if a strike is nearby but little or no thunder. Yet I can hear for 30 seconds or so after a distant flash when the thunder ...
23
votes
3answers
731 views

How good were climate models of the 1990s at predicting the global temperature trends of the 2000s/2010s?

Was there a significant bias between the ensemble of climate models and the long-term temperature trends? What about spatial patterns?
11
votes
1answer
3k views

Winds in a northern hemisphere hurricane

In the Northern Hemisphere, do surface winds around the center of a hurricane move counterclockwise and inward or counterclockwise and outward? I'm guessing they move inward.
12
votes
2answers
154 views

What is a source of worldwide temperature data that also includes extreme weather?

I often need to calculate heat balances for large biogas plants, an important factor is outside temperature. I normally use the weather data from Klimadiagramme.de where I can find the mean monthly ...
14
votes
2answers
6k views

July/August hottest months (northern hemisphere): because of continued warming or other effects?

In the northern hemisphere, July and August are the hottest months statistically1, but the days start shortening after June 21st. Is this just because the Northern Hemisphere keeps heating up after ...
14
votes
3answers
15k 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 ...
11
votes
3answers
229 views

Is it right practice to validate temperature data with reanalysis data?

For a project I am working on I received raw data from many meteorology stationes. Is it right practice to test this data against air temperature from noaa's ncep/ncar data?
19
votes
2answers
15k views

Where can I get archived hourly temperature data?

I am looking for historical hourly temperature data from many cities in the US what other data sources are there except wunderground? UPDATE: I will use the data to compare stations from the same ...
11
votes
1answer
219 views

Synoptic weather predictibility under climate change scenarios

Under climate change scenarios, it is quite certain that high latitude regions will experience more warming than at low latitudes. For example, in winter the reduced area of sea ice and snow cover ...
24
votes
2answers
2k views

What is the steepest surface that can hold snow?

I know it depends on the type of snow (dry or wet) and the rougness of the surface. I'm looking for an approximate rule of thumb answer. Assuming a reasonably smooth surface, at what angle it's likely ...
10
votes
1answer
6k views

What is the primary cause of the “Norwester” winds that affect parts of India & Bangladesh?

I am primarily interested to know: What is Norwester (localy called Kalboishaku as because in occurs during the Bengali Month Boishak which falls between Mid April to Mid May). What causes Norwester....
14
votes
1answer
245 views

How do climatologists define the “start” of a rainy season in a unimodal monsoonal climate?

For a number of gridcells, all between the 500mm and 800mm rainfall isohyets in sub-Saharan Africa, I've got dekadal rainfall (from FEWS). They are pretty spread out over the continent and there are ...
13
votes
5answers
4k views

How to reduce the atmospheric temperature artificially?

Is there any gas/substance which absorbs/reduces atmospheric temperature? Ozone filters UV rays from the sun light and allows in infrared rays. In my knowledge these infrared rays are the cause of ...
11
votes
2answers
315 views

How do meteorologists grade their past forecasts?

In every professional field, practitioners may come home at the end of the day and say "Yeah! I knocked it out of the park!", or alternatively "Oh, man. Gotta do better tomorrow." What about ...
17
votes
1answer
5k views

What is the range of possible atmospheric pressures on the surface of the Earth?

I'm developing an Android app which uses a pressure sensor. Due to storage limitations I have to normalize and scale the atmospheric pressure values. For this I need to know the extreme values of ...
3
votes
0answers
86 views

Is the number of high/low pressure regions different at low pressure levels at high pressure levels?

Is there a higher number of mid-latitude high/low pressure regions at 850 mb, as compared to the number of high/low pressure regions at 200 mb? And if so, why?
8
votes
1answer
226 views

How does El Niño affect thunderstorm/tornado/CAPE activity in the central United States?

Or in other words, does it increase the amount of heat+moisture advection from the Gulf of Mexico into the Central United States? And is this increase associated with increased CAPE/tornado/...
1
vote
1answer
583 views

How to perform precipitation data analysis? [closed]

I want to make precipitation data analysis for the Latvian territory. I only have meteorological stations and reanalysis data. My data from meteorological stations are in the format: ...
14
votes
1answer
626 views

How long does it take for the atmosphere to mix?

If I release a say, one litre of gas, at a particular point on the planet, how soon, on average, would it take to be distributed evenly (mixed) across the entire earth's atmosphere?
28
votes
1answer
2k views

What factors determine the number of Hadley cells for a planet?

We know (think?) that Earth has three Hadley cells per hemisphere, but from observing gas giants such as Jupiter, we see that they have many more cells. According to a link from a comment in this ...
8
votes
1answer
9k views

Why does the wind periodically change direction?

Image Subtitle: Wind going across the page - and changing direction To clarify, imagine you were sat in a boat in the middle of a lake recording the wind direction every minute. You notice that the ...
8
votes
1answer
415 views

How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's climate?

I was thinking about this question, which may turn out to be simple, about climate dynamics: How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's ...
7
votes
1answer
190 views

Why is the warm phase of the Pacific Decadal Oscillation associated with stronger El Niños?

This is a question inspired by the post at Cliff Mass Weather Blog: "Is a Super El Nino Coming Next Winter?". There is something else. You ever hear of the Pacific Decadal Oscillation? This is ...
12
votes
1answer
2k views

Is there any correlation between La Niña/El Niño and seismic activity?

I've read in the past that extreme precipitation levels may have an effect on seismic activity, and wondered if anyone has ever analysed the La Niña / El Niño cycles to see if there are any ...