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# 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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14k 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)....
824 views

### Evaporation loss formulas

A while ago I created a spreadsheet to calculate evaporation loss. I found several formulas to do that, two from Kevin Rafferty and one from Engineering Toolbox. The one from Engineering Toolbox was ...
106 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.
809 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. ...
2k 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?
44k 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 >...
1k views

### Why are clouds darker before it rains?

What causes the darker color of the clouds (nimbus) when it is about to rain? Non-precipitating clouds (e.g., cumulus, stratus) tend to be white, but rain clouds become gray and almost black before it ...
3k views

### Why do clouds sometimes form a ring around the Sun?

Someone shared a video with me in which clouds were forming a ring around the Sun. I took this screen shot of that video: What is the reason behind this?
364 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 ...
6k views

### What does the notation “kg kg-1” for units mean for specific humidity

I am using a data set from Justin Sheffield at Princeton that includes specific humidity. The description is as follows: "Reanalysis 6-hourly specific humidity interpolated to 1.0deg with account ...
179 views

### Eliminating range folding error in doppler radar returns

With weather radar, it's not uncommon to see large areas of the image blocked out due to detected range folding. It's my understanding that this occurs when a reflection outside of range comes back ...
3k views

### Why do certain areas on Earth have a higher or lower air pressure at sea level?

For instance, looking at this map of world air pressure in January and this map of July, why do some land surfaces have a higher pressure during the winter? I know that the tropics and Coriolis ...
695 views

### How can daily brightness be quantified or measured?

It occurred to me that there might very will be a metric out there that measures and quantifies "daily brightness". Meaning, how bright any given day is, taking weather conditions and cloud coverage ...
3k views

### Are lightning storms more common at night?

I have, to my knowledge, seen far more lightning strikes and heard more thunderclaps at night than I have during the day. Are lightning storms more common at night, or are they just more noticeable ...
919 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 ...
961 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. ...
176 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 ...
589 views

### Why is the colour gradient in the sky at sunset on an angle?

Below is a picture of a typical sunset that I have been observing lately at an undisclosed location in the Southern Hemisphere: Given that the base of the picture is parallel to sea level, you can ...
134 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 ...
3k views

### Wet and dry seasons - what are they and how do they form?

While asking questions on Worldbuilding, I keep hearing about wet/dry seasons. Obviously, one has rain and the other doesn't, and I've gathered that they occur with regularity on an annual basis, but ...
585 views

### How and why humidity and vapour pressure change as a parcel of air with an unchanging amount of water vapor rises, expands, and cools

I know that a parcel of air can rise, cool and create clouds and rain but I'm struggling to understand how: absolute humidity relative humidity actual vapour pressure saturation vapour pressure ...
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 ...
26k views

### Is a complete global flood physically possible on Earth?

Genesis 7:11-20 presents an account of a precipitation event which, in 40 days, submerges the entire surface of the earth: [On] the seventeenth day of the second month — on that day all the ...
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 ...
152 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 ...
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 ...
157 views

### Dependence of solar irradiation through the atmosphere on Sun's altitude

I want to show that the higher the Sun's altitude, the higher the solar irradiation through the atmosphere, through simple experiments. However, I don't have the instrument that measures irradiation. ...
935 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 ...
180 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 ...
4k views

### What causes the 'calm before the storm'?

The old adage "The calm before the storm" certainly has an observational scientific meaning to it -- something that many (including myself) have experienced -- that on a hot summer's day, when a ...
122 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 ...
145 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 ...
175 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 ...
414 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 ...
2k 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 ...
1k views

### Minimum sea-level pressure and maximum wind speed intensity relationship in Hurricane Katrina (2005)

Hurricane Katrina was one of the deadliest and most destructive hurricane to hit the US. After looking into the minimum sea-level pressure (MSLP) and maximum wind speed (MWS) intensity data from NOAA'...
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 ...
505 views

### Two severe cyclones connected by a monsoonal trough

At the time of writing, areas around the Northern Territory (TC Lam) and Queensland (TC Marcia) in Australia are in the path of severe cyclones (category 4 at the moment, with the Queensland one - TC ...
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,...
184 views