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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5
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0answers
195 views

Bulk and dynamic viscosity in the atmosphere

I'm studying the physics of the atmosphere but I'm struggling with the matter of viscosity (Navier-Stokes equation) for gravito-acoustic waves. From Landau-Lifschitz : $$ (T)_{ij} = -p\delta_{ij} + \...
7
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1answer
374 views

What are the advantages in looking at an OLR map versus looking at IR satellite imagery?

Conceptually they seem to be showing the same information. But in the context of a Madden Julien Oscillation (MJO) or equatorial waves especially over the equatorial oceanic layers which one is more ...
18
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2answers
5k 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 ...
10
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1answer
622 views

Snow from Fire: Could graupel, or even snow, fall from pyrocumulus clouds?

Pyrocumulus clouds often form in areas that experience prolonged fire conditions, particularly forest fires, but are also associated with volcanic eruptions and even nuclear explosions. This question ...
15
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2answers
1k views

What factors affect the size of rain shadows?

Rain shadows are dry areas on the lee side of mountains. Due to humid air condensing and precipitating as they are lifted up and over the mountains, they lose moisture by the time they reach the lee ...
9
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1answer
147 views

Where does the symmetry of cloudy bands come from?

Reading Meteorology Fundamentals by Sylvie Malardel, it says: We observe a symmetry of the cloudy bands with respect to the rotation axis of Earth and between Northern Hemisphere and Southern ...
13
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1answer
1k views

How significant is a 5-10 mb drop in pressure over a 20 minute period?

I would be interested in seeing how significant a 5-10 mb drop in pressure would be at the surface, and 80 m in the air. The temporal scale would be 20 minutes. If the pressure starts to steadily ...
13
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1answer
863 views

Dry atmospheric temperature profile (dry adiabatic vs. isothermal)

I'm trying to understand why there are differing predictions of the atmospheric temperature profile. It is well established that the dry adiabatic lapse rate (DALR) is: $$ \frac{\mathrm{d}T}{\mathrm{...
11
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1answer
2k views

Intuitive explanation of precipitation amount

I'm trying to learn how to make sense of numbers in a forecast. I can interpret temperature and wind speed, but I don't know what to make of rainfall. What does it mean, for a human, that there will ...
7
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1answer
914 views

Statistical weather prediction

Assuming I have time evolution of air temperature, air pressure, wind speed, wind direction, relative humidity and cloudiness, how can I predict weather based on this information? I know that high ...
15
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1answer
360 views

What is the predictability of El Niño/La Niña?

What is the maximum period of time into the future that an El Niño event can be forecasted with reasonable accuracy and what are the limitations in predicting the time limit?
10
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1answer
310 views

Regarding various types of atmospheric pollution

Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and ...
8
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1answer
228 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/...
8
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0answers
142 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 ...
3
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0answers
89 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?
7
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1answer
356 views

LWC and Absolute Humidity

What is the difference between "liquid water content" and "absolute humidity" in meteorology? Both have units of mass/volume.
9
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1answer
1k views

A parcel of air in an isothermal layer

I'm having a bit of trouble figuring out a solution to this problem: There is an isothermal layer of air which has a temperature of 0 °C extending from the surface to 1 km height. A parcel is 0.5 °C ...
3
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3answers
1k views

Regarding the melting glaciers and icebergs, why isn't the extra water vapor in the atmosphere mentioned in discussions of global warming?

As is reported on the major news networks, many glaciers and big icebergs are melting, which reportedly causes a tremendous increase in the amount of water vapor in the atmosphere. Now a lot of ...
10
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2answers
1k views

Why is q used for specific humidity?

$q$ is the symbol used for specific humidity in many textbooks and papers (at least in meteorology and climatology, I'm not familiar with it in other disciplines). Where does this symbol come from, ...
6
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1answer
5k 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.
14
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1answer
481 views

Will dust storms be more frequent in the future?

I noticed that in some science fiction movies set in the future on Earth, like Wall-E and Interstellar, dust storms are very prominent. Are there any scientific hypotheses suggesting that dust storms ...
11
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1answer
2k views

What is the difference between an inertial instability and a symmetric instability?

Inertial and symmetric instabilities are fluid instabilities present in atmosphere and ocean. What are the difference between an inertial instability and a symmetric instability?
7
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0answers
437 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 ...
31
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1answer
3k 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 ...
9
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1answer
145 views

Why does air seem to affect local surface temperatures so much?

Last winter, several areas in the US and Canada were hit by a "polar vortex." I happen to live in one of those areas and was amazed how much the temperature seemed to change so suddenly just because a ...
10
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1answer
7k 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
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1answer
150 views

Have there been any attempts to measure profiles through deep convective systems using dropsondes?

In-situ measurements in deep convective systems, tropical cyclones, etc., are difficult to perform. Few if any people would like to fly a small aircraft close to its core, and radiosondes or larger ...
7
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2answers
680 views

Relationship between illuminance and cloud cover

Is there a clear formula or table relating the illuminance in (lux) to status of the sky in terms of cloud cover? For example, mostly cloudy would be 2000-3000 lux.
7
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1answer
470 views

Pressure as a function of altitude

My city's altitude is almost 950 meters, yet the weather stations provide a read of 102.14 kPa which is around 1 atm! Shouldn't the pressure be a function of elevation? I doubted that the data ...
14
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2answers
1k views

Why don't cold fronts and other steep-gradient weather effects just dissipate?

Why don't cold fronts and other steep-gradient weather effects just dissipate? Why do they last so long? Why doesn't the heat dissipate toward the cooler region?
12
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1answer
223 views

Why is heavy precipitation from atmospheric rivers more likely to hit the West Coasts than the East Coasts?

As an example of an atmospheric river, see http://www.wired.com/2014/03/california-atmospheric-river-rain/. These events have been known to hit areas like California and Bergen, Norway.
9
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1answer
1k views

How does the pole-to-equator temperature gradient scale with height contours?

Are the pole-to-equator temperature gradients lower at higher heights than at lower heights (like 850 mb/500 mb)? If so, why is it the case? Especially given that the zonal circulation tends to be ...
9
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3answers
896 views

What is the reason why there are radiosonde measurements in the atmosphere?

I have seen weather balloon measurements of air. Why is this done? Aren't the measurements we take on the ground enough?
32
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3answers
4k views

Why does Coriolis determine the rotation direction of a cyclone but not my drain?

It is a common misconception that Coriolis is responsible for the direction the water swirls down a toilet, tub or sink drain. E.g. does a toilet flush the other way in the southern hemisphere? (If ...
5
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1answer
626 views

How to determine that sustained wind speed exceeded the threshold value?

Certain maritime ports and airports have ranges of operation relation to the wind, usually according to a given threshold value of sustained wind speed. If I have the instantaneous values from ...
10
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1answer
757 views

Resources for learning the technical parts of atmospheric modeling

I'm a computer/atmospheric science undergrad and I'm trying to get into atmospheric modeling. Any recommendations for resources to get going or to learn about approaches? I can handle fairly technical ...
5
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2answers
335 views

Pressure of condensation of an air parcel

If a parcel of air ascends adiabatically, would condensation be reached at the lifting condensation level (LCL) or the level of free condensation (LFC)?
11
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1answer
713 views

Why is Montana warmer than Wyoming?

The National Climatic Data Center (NCDC) data shows the mean temperature from 1971-2000 for Montana was 5.97°C (42.74°F) and Wyoming's was 5.54°C (41.98°F). Montana is at a higher latitude, so this ...
14
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2answers
1k views

How can odor travel be tracked

Odd question, but what data would be needed to to calculate how far winds will carry a strong odor (such as the smells of a restaurant, pizza parlor or burning wood/building? There is wind direction ...
11
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1answer
288 views

Sea breeze - magnitude of horizontal pressure gradient?

What is the range of horizontal pressure gradients typically caused by the differential heating of land and water under sea breeze conditions?
7
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1answer
265 views

Resources to determine temperature probability for a given location on a given date

What tools or resources are available (free) on the web to determine the probability of a given point on the earth to be at or above (or below) a specific temperature on a specific date. Some [...
27
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3answers
4k views

Equinoxes and solstices: start of the season or mid-season?

In the United States, the upcoming autumnal equinox is marked on most calendars as the "first day of autumn." Similarly the solstices are commonly called the "first day of summer" and "first day of ...
13
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1answer
161 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 ...
11
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1answer
792 views

How much energy is needed to alter the path of a hurricane?

Suppose we spot an Atlantic hurricane very early. How much energy should we expend to alter its track: with nuclear detonations (let's forget about the side effects for the moment)? with a large ...
10
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1answer
1k 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 ...
18
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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 ...
10
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1answer
564 views

Why do rainbows appear to have a fixed structure?

Why do rainbows appear to have a fixed structure when a bunch of raindrops are 1. moving, and 2. granular?
8
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1answer
131 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 stratosphere. ...
8
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2answers
192 views

What determines the differences in results between various weather models?

It's often said that the ECMWF model is more accurate than the GFS. But what are the reasons why? Also, how does the NAM compare with these two and other forecasting models?