Questions tagged [humidity]
The level of water vapor in the atmosphere. Use this tag for questions about either relative or specific humidity.
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43 views
What is the difference between surface specific humidity and surface relative humidity?
What is the difference between surface specific humidity and surface relative humidity (it's wetter and dryer respectively)? The trends, according to the latest IPCC report, are opposite for the two, ...
3
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1answer
41 views
What Pa level should I use when looking at Relative Humidity data from CMIP6 models?
I have downloaded a number of future simulations for a group of GCMs from CMIP6 for the variable Relative Humidity (hur).
I chose the 100000pa level to view the RH data in panoply for the EC-Earth ...
3
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0answers
86 views
How can I deal with unrealistic Relative Humidities being calculated using vapour pressure and saturated vapour pressure?
I am calculating RH (%) using this well accepted equation:
$RH =e \times \frac{100}{es(T)}$
where $e$ is the vapour pressure and $es(T)$ is the saturated vapour pressure at temperature $T$.
I have ...
0
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0answers
29 views
What does DHW (Degree hours (base 0 C) when W= 1 ) mean?
I am reading a paper on A-Scab simulation model and there I saw an equation given in the picture
I am confused what does wetness (W) mean, as in is it a meteorological variable ??
Or does it mean ...
2
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0answers
42 views
Incorrect relative humidity with SHT30 when comparing to dry and wet bulb calculation
I am attempting to calculate wet bulb temperatures needed for agricultural curing processes. I am trying to do this by inferring the wet-bulb value from relative humidity and dry bulb temperature.
The ...
2
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1answer
106 views
How does a whirling hygrometer work, how does it differ from static dry/wet bulb thermometer, and how to obtain humidity from its readings?
Answers to my previous question How is relative humidity determined from a wet and dry bulb readings? provide equations for converting the two temperature measurements to a relative humidity.
In ...
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1answer
102 views
How to convert Relative humidity (%) or Specific humidity (kg/kg) to Air humidity (mb)?
The model I use needs the data of Air humidity and unit is 'mb' (there is no other explanations about this variable), but now I only have two datasets and there are Relative humidity (%) or Specific ...
3
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1answer
125 views
Why does relative humidity drop if I open the window in winter? What about the temperature drop?
I understand that 40% rel. hum. at 0 °C is less absolute humidity than 40% at 20 °C. However, assume that we have 2$~m^3$ of air. Both are 40% humid at 20 °C. Now we exchange 1$~m^3$ with air that is ...
2
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2answers
118 views
How to calculate the specific humidity based on the saturated specific humidity?
I am using ERA5 data to drive the land surface model. One of the forcing required by LSM is specific humidity. We want to use the 2-m specific humidity. So how can I calculate the specific humidity ...
7
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1answer
319 views
Relative Humidity approximation from Dew Point and Temperature
I would like to find a formula to approximate RH based on known air temperature and dew point. I need the approximation to be valid at least between -20...+40 degrees Celsius. I read the accepted ...
2
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2answers
509 views
What does supersaturation with respect to ice mean?
I've been reading about the Bergeron process, a process that generates much of the precipitation in the middle latitudes by generating ice crystals at the expense of water droplets. The part I don't ...
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3answers
221 views
How do the pros measure humidity?
I have used a wet/dry bulb setup to estimate humidity, and it appears that the Argentinian meteorological service uses one in Antarctica as well.
Wikipedia sez:
Humidity measurement is among the ...
6
votes
1answer
702 views
How is relative humidity determined from a wet and dry bulb readings?
The question What is the second thermometer in the image from the Esperanza Antarctic temperature record? shows what might be a wet/dry bulb setup.
I've given one to a friend to measure humidity for ...
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0answers
25 views
Finding free humidity data
I am trying to find historical humidity levels (ideally in percentage format) across the globe divided by sub-country regions or more granular.
The time granularity would be daily, but hourly would ...
3
votes
1answer
114 views
What the humidity metric is hiding?
So I have been spending time in Moscow Russia which essentially records very similar climatic humidity to my home city of London. However in Moscow my throat is permanently dry, I need to consume more ...
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2answers
112 views
Deserts and Humidity
How is that a general rule of thumb that less humidity equals more rain? Deserts don’t get much rain and humidity is also very low. Rainforests get a lot of rain when the humidity is very high so how ...
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1answer
99 views
Humidity and Rainfall
Usually the higher the humidity the more rainfall we get like in the summer here in Asheville, North Carolina we get a lot of showers and thunderstorms in the summer from the high humidity but I saw ...
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36 views
How does this calculate the water transport between crops in the webside?
click->http://gpe.letsgrow.com/
next click->moisture transport
In the results of Moist transport through the crop, what is the relationship between crop height and diffusion, air movement, and total ...
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1answer
51 views
Definition of Surface-based atmospheric duct
I am writing a literature review for a project and I have a problem. Namely, I cannot figure out the the condition required for surface-based duct to occur. Literature does not help either. In one of ...
3
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0answers
43 views
Oscillating dew point throughout the year?
I was searching for the climate of Saudi Arabia and I noticed that the city of Abha (altitude of 7000 feet) has a "strange" behavior in its dew point, as numbeo suggests: https://www.numbeo.com/...
3
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1answer
213 views
How does total pressure affect relative humidity and how do I correct my hygrometer for pressure?
Obviously pressurized air can hold more water than regular air, so an increase in overall pressure would result in an inversely proportional decrease in relative humidity. However, I can't seem to ...
7
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1answer
10k views
How to calculate relative humidity from temperature, dew point, and pressure?
Is there a formula given the temperature, dew point, and pressure to find relative humidity?
I have seen several calculators like this one, but I would like to know how to calculate this myself.
I ...
2
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2answers
446 views
Can minimum relative humidity be greater than maximum relative humidity?
I am trying to calculate minimum and maximum daily Relative Humidity values given a min/max Specific Humidity and min/max Temperature.
I found some equations here that work with the given variables, ...
5
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1answer
251 views
How to predict when contrails are likely to form over a specific location using public data?
I saw the image below used as a click-attractor to an unrelated story about tourism, but found a larger version here.
Contrails, or water condensation trails happen when planes pass through the ...
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3answers
13k views
Why does warm air "hold" more moisture?
It is often explained that warm air holds more water because warmer water is less likely to condense. This and other explanations just seem to be circular arguments. If the warmer air picks up enough ...
7
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1answer
299 views
How is the specific heat of a wet bulb determined?
I am quite new to the psychrometry and the study of humidity, and I'm currently learning about the dry-bulb wet-bulb thermometry. As far as my understanding goes, the wet bulb is connected to a source ...
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1answer
823 views
Water vapor content versus specific humidity
I am wondering the difference between water vapor content and specific humidity to determine the moisture availability in the atmosphere. Which one is more acceptable variable to determine the ...
5
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1answer
1k 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 ...
6
votes
1answer
4k views
How to calculate humidity using outside temperature and outside relative humidity?
I would like to ask how to calculate the relative humidity that a heated indoor area would have using only outside temperature and outside relative humidity.
I found the Relative Humidity Calculator ...
2
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0answers
1k views
Is this an accurate simulation of a further south Australia with a filled lake Eyre?
I created this climate map based on a simplified Koppen Climate Classification map (shown below). In this scenario Australia is moved 10 degrees of latitude further south and the Lake Eyre basin is ...
2
votes
1answer
82 views
Why a stratus cloud does not always reach all the way to the ground?
The surface of the ground at night cools down because of outgoing long-wave radiation. In my understanding the cooling of the surface also causes cooling of the adjacent air. If the air contains ...
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1answer
1k views
What is the mixing ratio of a cloud?
A cloud has relative humidity of 100% or more. Is it correct to say that the mixing ratio of a cloud is undefined? My reasoning is that dry air in a cloud is negligible therefore $w = \frac{x g}{ 0 kg}...
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5answers
706 views
Why does relative humidity seem to correlate with high temperature (at least where I live)?
I live in New Jersey. Now that summer is coming on us, temperatures and outdoor relative humidity are both increasing. I've noticed the few years that I've lived here that there seems to be a rough ...
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3answers
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Is there a name for these "pouring" clouds?
I snapped this photo with my phone flat against the window of a bus, facing south while traveling west across a bridge in New Taipei City. I'd say it was at about 24.995N, 121.438E. It was about 14:00 ...
3
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1answer
2k views
Why do anticyclones bring clear skies in summertime?
It's obvious that in summer anticyclones bring hot weather. But why clear skies?
Heat evaporates the moisture and should lead to the cloud formation, shouldn't it?
3
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1answer
3k views
How does humidity vary with height in the Earth's atmosphere?
I am busy with the development of an "environment" model that can be used for flight simulation of all kinds of flight vehicles — ranging from quad-copters, unmanned aerial vehicles, manned aircraft, ...
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1answer
933 views
Why (actually) is the night sky so bright in the city? How far up is that happening?
The recent news reported by the New York Times, the BBC and the NPR web sites (for example) as well as in the Iceland Review and Iceland Magazine sites, about the shutting-off of Reykjavik's ...
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1answer
790 views
Mild climate, low-humidity city all year round [closed]
Where in the world can I find a place with mild / warm and non-humid climate all year round?
What I'm looking for is a city with these characteristics:
- monthly average low temperature > 5°C (41°F)
-...
4
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2answers
9k views
Can relative humidity be over 100% near (within 30-60m) the surface?
I am processing a big meteorological data set, which is a global forcings dataset derived by other datasets and observations, and calculating relative humidity from qair,temperature, and pressure ...
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4answers
9k views
Is it hotter in different places with the same air temperature?
I am from (and live in) Minnesota, USA. In the summer here it always reaches temperatures in the 90s (F) for periods of time but not every week. The humidity is often high and the dew point often ...
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1answer
97 views
How strong is the correlation between the dew point of a town and the seawater temperature next to that town?
For example, the towns that has the highest dew point are usually next to the Red Sea and the Persian Gulf where the seawater temperature exceeds 30 degrees in summer.
3
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1answer
506 views
Accurately Measuring Indoor/Outdoor Air Temperature & Relative Humidity
I’m conducting an independent study as a concerned citizen on the indoor temperature at an animal shelter to support the need of improved air conditioning by documenting how hot it can reach during ...
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2answers
2k views
Does usual city pollution have effects on relative humidity?
I've noticed that in a rural area with low pollution the relative humidity is constantly lower than the humidity in a high polluted city. Is there any correlation between pollution and humidity?
5
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2answers
6k views
Why doesn't it snow even when it is below freezing?
I know the temperature of a place is determined by various factors, a few of which I can think of are: Altitude, distance from sea, latitude, wind etc.
My question is basically regarding latitude. ...
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0answers
30 views
Can humidity changes induce stacking-sequence changes?
My understanding is that some minerals with layered crystal structures will reversibly absorb water with changes in humidity. Are there any minerals where this reversible absorption leads to a ...
9
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1answer
21k 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)....
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1answer
986 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. ...
30
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2answers
54k 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 >...
10
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3answers
11k 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 ...
4
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1answer
796 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
...
