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.
169
questions
35
votes
1
answer
6k
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 ...
- 1,833
23
votes
1
answer
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?
- 1,524
31
votes
2
answers
44k
views
Why are there no hurricanes in the southern Atlantic basin?
We see tropical cyclones (going by different names e.g. hurricane, typhoon, cyclone) all over the tropics, but it seems that there are never any storms in the southern Atlantic. See this map of ...
- 2,758
21
votes
4
answers
24k
views
What would be the effect of bringing seawater pipes to the Sahara desert?
This is a childhood dream.
What would happen if pipes were installed (similar in principle to the Great Man-Made River, but for seawater) to continuously pump seawater into the Sahara desert.
Let'...
- 311
9
votes
2
answers
3k
views
How to compute du/dx and dv/dy in moisture flux convergence?
I have $u$-wind, $v$-wind and specific humidity. I would like to compute moisture flux convergence at a grid point. So I need to compute the value of $q(\frac{du}{dx} + \frac{dv}{dy})$
My question is ...
- 461
30
votes
3
answers
6k
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 ...
- 451
22
votes
2
answers
6k
views
What are the major differences between weather models and climate models?
Some weather models include GFS (Global Forecast System) and NAM (North American Mesoscale Model).
Some climate models include CCSM (Community Climate System Model) and the NASA GISS (Goddard ...
- 7,817
19
votes
2
answers
9k
views
Why does the Hadley cell descend at 30 degrees latitude?
George Hadley's initial model of the Hadley cell described air as being heated at the equator, ascending, and then moving aloft pole-wards where it would cool and descend. Meanwhile surface air would ...
- 7,626
17
votes
2
answers
7k
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 ...
- 2,669
11
votes
1
answer
862
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 ...
- 219
6
votes
1
answer
2k
views
How can temperature be calculated given relative humidity and dew point?
While looking into the better indicator of how miserable it feels outside, either dew point or relative humidity, I came across this statement:
The optimum combination for human comfort is a ...
user11318
4
votes
1
answer
306
views
What is the second thermometer in the image from the Esperanza Antarctic temperature record?
Today, the Argentinian meteorological service tweeted about a new temperature record for Antarctica of 18.3°C, made on the Espezanza peninsula. This was subsequently reported by many other sources.
...
- 817
90
votes
3
answers
40k
views
Impossible or improbable? Hurricane crossing the equator
No known hurricane has ever crossed the equator. Hurricanes require the Coriolis force to develop and generally form at least 5° away from the equator since the Coriolis force is zero there.
Are ...
- 2,658
32
votes
4
answers
5k
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 ...
- 1,920
30
votes
2
answers
63k
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 >...
- 403
27
votes
3
answers
83k
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.)?
- 5,435
24
votes
3
answers
1k
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?
- 7,817
16
votes
1
answer
612
views
How will cloud feedback effects on the climate change as the result of global warming?
So global warming will increase the tropospheric temperatures, which, in turn, would make the clouds higher than they otherwise would be.
And higher clouds (especially cirrus clouds) tend to trap in ...
- 7,817
15
votes
1
answer
3k
views
What is the formula used for atmospheric visibility?
I am working on NCEP GFS data to plot various maps. One such plot I would like to have is visibility. I have seen some of the sites showing visibility charts and the source of the data was shown as ...
- 375
15
votes
3
answers
3k
views
What causes these banded clouds?
A set of banded clouds can be seen in MODIS imagery during several days in January and February over the Gulf of Maine. They tend to occur with very cold winds from the NW following storms.
There are ...
- 15.4k
9
votes
1
answer
30k
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)....
- 667
8
votes
1
answer
14k
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 ...
- 91
7
votes
3
answers
1k
views
Why are inversion layers so important in meteorology?
I keep hearing the term "inversion layer" when reading about pollution and meteorology.
I know it vaguely amounts to "some place where the gradient of temperature is inverted".
But why are inversion ...
- 173
7
votes
2
answers
12k
views
Which clouds can produce lighting and thunder?
There are several number of cloud types, but I only know that cumulonimbus clouds discharge electricity, which in turn produces thunder and lightning. Is this type of cloud (cumulonimbus) the only ...
- 363
5
votes
1
answer
2k
views
How would I use data to find specific humidity and mixing ratio?
I keep reviewing this table to compare and contrast my results:
The parcel of air is at 35°C and a relative humidity of 43%.
I used this online calculator and it stated that with these two factors ...
- 485
3
votes
1
answer
221
views
What are these Gizmos at Mauna Loa Observatory?
Artist Rosten Wu's Vimeo channel has a video title Bridging Time and there is discussion about the Keeling Curve and the site where it all began in Hawaii.
In the video there is a shot of a weather ...
- 6,904
26
votes
3
answers
9k
views
What do weather forecasters mean when they say "50% chance of rain"?
What do weather forecasters mean when they say "50% chance of rain"?
Even more confusing: weather report often says something like "30% chance of rain. >10mm", then the next day "70% chance of rain &...
- 5,435
24
votes
1
answer
20k
views
Do tornadoes have eyes?
In the movie Into the Storm (2014) near the end, storm chaser Pete sees the eye of a massive tornado.
In 1928 (real life), Will Keller was in his barn when a huge tornado passed through. He reported ...
- 343
23
votes
2
answers
945
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 ...
- 333
22
votes
5
answers
4k
views
Is there a database of global rainfall time series?
Is there any institute out there collecting time series data of precipitation, and making them accessible online? I need data for a few different locations, but:
Low spatial resolution is fine. For ...
- 405
21
votes
6
answers
29k
views
Why doesn't the sun reach its highest point overhead at exactly 12:00 noon?
Many sources state that 12:00 noon is the high-point or mid-point of the sun's path across the sky.
However, for where I am, this is obviously wrong. In my own town the high point of the sun occurs ...
- 313
20
votes
5
answers
6k
views
Is it true that a butterfly flapping its wings can result in a tornado in a distant location?
I have heard that extreme storm events can be caused simply by a butterfly flapping its wings somewhere in a distant location. Is it true that such a small disturbance in the air in one location can ...
- 7,626
19
votes
2
answers
17k
views
Where is the calmest place on Earth?
I have done some research online, and I've found out that Antarctica has the calmest winds (lowest maximum wind speed) recorded on Earth. However, it is uninhabitable for human life. Other very calm ...
- 1
18
votes
1
answer
1k
views
Why do tropical cyclones not tear themselves apart?
A tropical cyclone is the generic term for a hurricane, typhoon, or tropical storm. Tropical cyclones derive their energy from evaporation of water at the ocean surface which ultimately recondenses ...
- 1,941
17
votes
3
answers
30k
views
Why does the Inter tropical Convergence Zone shift?
I am currently learning at school about the climatic conditions (mainly winds, difference in pressure, Coriolis effect, etc.) that cause and affect the monsoons received by India.
One of the factors ...
15
votes
2
answers
6k
views
Why are weather service atmospheric pressures systematically different from those I measure in Johannesburg?
I live in the northern suburbs of Johannesburg in South Africa.
I have noticed while working with synoptic weather charts in geography class that the isobars indicate that Johannesburg should have ...
- 153
14
votes
2
answers
4k
views
Why is the Atlantic Hurricane Season defined as being between June 1 and November 30?
Historically, the Atlantic Hurricane Season has shifted, as close as June 15 to October 31, but since 1965, it has been between June 1 and November 30(1).
Why is the Atlantic Hurricane Season defined ...
user402
14
votes
4
answers
8k
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 ...
user1066
13
votes
2
answers
516
views
How to tell if fog is made out of water droplets or ice crystals?
I understand that clouds can be made out of water droplets and/or ice crystals. And that fog is nothing else than low-lying clouds.
However, I've experienced fog in a wide ranges of temperatures. I ...
- 17.7k
13
votes
1
answer
3k
views
Why is WRF most often configured at 3:1 nesting ratio?
In WRF application, nested domain has always been used for weather/air quality modeling for the place of interest in a better resolution. The figure below illustrates this:
I have noticed that the ...
- 2,479
13
votes
2
answers
4k
views
Why are the clouds white and Australia black in weather satellite infrared images?
The question Is the sunlight on the GOES-16 Imagery reaching from the east? shows a visible light image and so in the night areas the Earth appears dark and in the day areas the Earth is a bit ...
- 6,904
12
votes
3
answers
610
views
Water on Mars and Earth
If water on Earth came from meteorites, why doesn't Mars have substantial water? What made it more highly probable on Earth than on Mars?
- 637
12
votes
1
answer
8k
views
Plotting wind barbs in python
I'm trying to plot wind barbs in basemap and I have two separate netCDF files.
Here is what I am trying to produce, or something like it:
How do I read a uwnd variable in a netCDF file in python?
<...
- 131
11
votes
1
answer
1k
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 ...
- 2,103
10
votes
2
answers
6k
views
What causes a rainbow, its colours and its shape?
What is the cause of rainbows? Do they appear due to rainfall or any other natural phenomenon. What makes it form a semi-circle in the atmosphere and its colours?
- 628
10
votes
4
answers
2k
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 ...
- 13.8k
10
votes
1
answer
14k
views
Is it typically colder after a storm?
I've heard that it's colder after a storm. I think this is an interesting question, not least because of the implicit comparison: colder than what? A few different comparisons come to mind, and still ...
- 201
8
votes
2
answers
497
views
What are these Gizmos at Izaña Atmospheric Research Center in Spain?
This tweet from the account of the Centro de Investigación Atmosférica de Izaña (AEMET) http://izana.aemet.es Izaña Atmospheric Research Center (AEMET) shows images of meteorological instruments ...
- 6,904
8
votes
1
answer
1k
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 ...
- 567
8
votes
1
answer
2k
views
Why is it colder in the mountains than at sea level?
I have heard numerous reasons why that is. I just want to know which one is right.
- 351