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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9
votes
0answers
136 views

Is there a distinction between gap winds and channelled flow?

I have seen gap flows mentioned in the literature, for example [Gohm et al. 2004, Zängl 2002, Mayr et al. 2007]. Whiteman 2000 defines a gap as a "major erosional opening through mountain ranges" and ...
11
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1answer
294 views

How are low pressure zones tracked across the ocean?

When you look at a surface pressure chart e.g.: (from http://www.metoffice.gov.uk/public/weather/surface-pressure/#?tab=surfacePressureColour&fcTime=1437480000) you can see low pressure zones ...
10
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2answers
220 views

How do the various types of clouds affect the atmosphere below them in a polluted environment?

I am working through this problem on my own as well, but am feeling that some perspective is in order. So, ignoring the obvious effects where precipitation will wash stuff out of the air, and blocking ...
8
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1answer
384 views

What is this cloud formation?

What is the cloud formation in this video? I don't know where this footage was taken. Here's the link to the video again.
7
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2answers
263 views

Are Southern Hemisphere 'Polar Blasts' caused by global warming?

The SMH journalist writes about a cold snap hitting the East Coast of Australia in July 2015: Proof of the big chill will be the extent of regions across Tasmania, Victoria and NSW experiencing zero ...
4
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1answer
80 views

How can I define frost based on a weather record?

If I want to (programatically, in a plant growth model) define a growing season as last frost in spring to first frost in fall, how might I determine these dates based on a weather record that ...
8
votes
1answer
17k views

How to calculate specific humidity with relative humidity, temperature, and pressure

I know there is this question already How do I convert Relative Humidity into specific humidity but I don't have ρws = density of water vapor (kg/m3) and ρ = density of the moist or humid air (kg/m3)....
3
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2answers
110 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.
6
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1answer
902 views

Specific humidity range in tropical lowlands?

I am running a land biosphere model that uses meteorological data as drivers. The model has a threshold of 32g/kg for specific humidity. The data I am using taken from a reanalysis performed by J. ...
4
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1answer
3k views

How do I convert Relative Humidity into specific humidity [duplicate]

I am using NCEP_DOE reanalysis 2 data set. It include only relative humidity while I need specific humidity. How do I convert the relative humidity into specific humidity?
5
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1answer
380 views

What is “focus point” in WRF-plots grid box? (python code)

has anyone used the python code from here (written by Geir Arne Waagbo) to plot skewT plot from WRF output? I've got a question regarding some of the functions used in the code found in ...
13
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4answers
990 views

How to tell if a single day of weather is an anomaly or due to climate change?

I am interested in understanding how to tell if a single day of 'abnormal' weather is due to climate change or not. From my understanding, you would compare this day's weather to historical weather. ...
7
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1answer
1k views

Why do the dry and moist adiabatic lapse rates converge with height?

Near the surface, the slope of the moist adiabats are much steeper than dry adiabats due (as I understand it) to the the latent heat released as water vapour condenses. The difference is amplified at ...
11
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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.
11
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2answers
180 views

What ice phenomenon are we seeing in this video?

I don't know what this YouTube video shows, but it appears to be half glacier and half "the blob." It almost appears to be "growing" although I assume it's being pushed somehow. Can someone tell me ...
12
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1answer
188 views

Are the “polar vortex” and “cut-off lows” over/near the Great Lakes new phenomena?

In recent years, I've heard weather reporters describe "cut-off" low pressure systems which park over Southern Ontario for days at a time. In summer months, they bring us long stretches of cool cloudy,...
19
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1answer
5k views

Where does wind come from?

Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air. What forces would cause such a mass movement of air?
7
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1answer
161 views

Strangely bright morning twilight over Switzerland

Yesterday morning (04.11.2014) I woke up at 6:40 as usual and noticed that it was relatively bright out. I had a better look around 7 and concluded that it was definitely quite a bit brighter than it ...
1
vote
1answer
137 views

Tornadoes meeting with an Immovable, Unbreakable, Large Cube

What would happen to a tornado if a Large, Immovable, Unbreakable and Obsidian Cube was in its path? The tornado is on a flat plain... but is heading towards the cube. By large, I mean the length of ...
16
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1answer
2k views

How do urban areas affect rain?

Urban areas these days can be quite large, and they can have strong effects on the environment: the urban heat island effect being the most obvious, but there may be other, more subtle effects. The ...
6
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4answers
2k views

Does “wind” include the air molecules involved, or merely the kinetic energy?

This question is about a riddle in which the statement "I am weightless" was made, and the answer was "wind". I want to know, by definition, does the wind include the air being moved, and thus have a ...
5
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1answer
192 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 ...
7
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1answer
69 views

How big is the influence of tree leaves on global windsystems?

As anybody knows, there are a lot of forests. I stumbled upon the question whether these have any effect on the global wind-systems. Imagine the following situation. All trees suddenly die in an ...
14
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3answers
12k views

What is El Niño Modoki?

What are the characteristics that distinguishes a El Niño Modoki from a "normal" El Niño? What are the effects of El Niño Modoki on atmospheric and oceanic processes? How does it affect weather ...
5
votes
1answer
92 views

Where can I find solar radiation data for specific land areas?

NOAA has solar radiation data for 1991-2010 http://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/solar-radiation But I need data for Nov 1 2012-present! Is this data ...
3
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2answers
1k views

What is the life-cycle of agricultural water used to grow crops/animals?

A là this Slate article: 1 gallon of water is required to grow a single almond 220 gallons to grow a large avocado 5,000 gallons to grow 1 lb of beef None of these things weighs anywhere near ...
5
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0answers
182 views

Is there anywhere on Earth *without* a rain shadow where we would otherwise expect one?

My understanding of rain shadows is that they occur in a region where year-round wind direction is the same (or nearly so), and there's a mountain range close by, such that the mountains block ...
9
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1answer
157 views

How would weather change on a tidally-locked terrestrial planet?

On Earth, weather is very much affected by the Earth's rotation around its axis and around the Sun. Even locations that are almost on the equator do have strong annual variations in precipitation and ...
7
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1answer
123 views

Vortices in the Atmosphere Sustained only by PGF

In a cyclone, the pressure gradient force (PGF) and the Coriolis force sustain the spinning motion and causes the direction of spin (counterclockwise in the Northern Hemisphere and clockwise in the ...
7
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1answer
179 views

The spiraling cyclone track - Cyclone Nathan

In the northern part of Queensland, Cyclone Nathan has had a spiral type of track, as can be seen below: Image credit: Tropical Cyclone NATHAN Forecast Track (Joint Typhoon Warning Center) As can be ...
29
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4answers
4k views

How do weather models work?

We use different weather models all the time, such as the ECMWF and the GFS. These models are simply amazing to me. How do these models work? I know they have to take in various data points - what ...
8
votes
3answers
443 views

Predicting school closures with historical weather prediction data?

I'm interested in predicting when the local schools will be closed due to snow and other winter weather. I have a list of school closure dates and a rough sense of the criteria used to determine the ...
23
votes
1answer
2k views

What causes 'positive' lightning to be rarer, higher charged, and longer lasting than 'negative' lightning?

Why is 'positive' lightning rarer, brighter, higher charged, and longer lasting than 'negative' lightning? Are there any other unique characteristics to positive lightning that sets it apart from ...
15
votes
1answer
288 views

What is the status of meteorological data exchange standards?

How do the web services exchange meteorological data? One method is transferring NetCDF and GRIB data and hooking them up to your software. I read here about the possibility of using WFS and WCS. ...
11
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1answer
2k views

Why do tropical cyclones around Australia have erratic paths?

According to the Australia Bureau of Meterology: Research has shown that cyclones in the Australian region exhibit more erratic paths than cyclones in other parts of the world. A tropical ...
22
votes
2answers
823 views

How can the average coldest day of the year be before the winter solstice?

There are parts of the U.S. where, on average, the coldest day of the year comes before December 21st. [source] How can this be? Why would temperatures start rising again even while days are still ...
12
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1answer
1k views

Numerical weather forecasting - resources for a programmer?

There is a community wiki question over at A good book or source for climate science and meteorology basics? that talks about meteorology basics. Building on that, but with a slightly different focus,...
13
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4answers
6k views

How to get cell indices from latitude and longitude in WRF model grids?

I am using Weather Research and Forecasting model WRF and the WRF Preprocessing System WPS and could not get a satisfying answer from wrfhelp. Can anyone guide me in transforming latitude and ...
5
votes
0answers
190 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
votes
1answer
370 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
votes
1answer
596 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
votes
2answers
951 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
votes
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
votes
1answer
989 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
votes
1answer
821 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
903 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
votes
1answer
355 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?