# Tag Info

### Why would it be drier indoors during the winter vs the summer?

The only physics you need to know is that if the temperature is higher the air† can hold more water vapour (the gaseous phase of water). Cool molecules don't have enough energy to free themselves from ...
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### At what humidity does it start to rain?

Short answer: humidity is not a proxy for rain starting and no, it does not start raining automatically when 100% humidity is reached (haze or clouds can form though). The onset of rain is dependent ...
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### How do I convert specific humidity to relative humidity?

Relative humidity is just $e/e_s$, the ratio of the vapor pressure to saturation vapor pressure or $w/w_s$, the ratio of mass mixing ratios of water vapor at actual and saturation values. If you have ...
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### How do I convert specific humidity to relative humidity?

Here is an implementation that I wrote in R (with documentation in the header). In addition to laboriously working through a few textbooks and online references, I have compared the results to a ...
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### Why (actually) is the night sky so bright in the city? How far up is that happening?

What's actually happening is scattering of light, both off of aerosol particles and nitrogen and oxygen molecules. For a review of quantitative models of light pollution as a function of distance ...
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### Why would it be drier indoors during the winter vs the summer?

Because cooling air tends to take out moisture, while heating air doesn't change the actual moisture levels. When air gets colder, it can't "hold" as much water vapor (lower saturation vapor ...
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### Why does warm air "hold" more moisture?

Saying that warm air "holds" more moisture is technically incorrect, but is a common colloquialism. Let's break it down to the technicalities. Let's consider a glass of water with a vacuum (no air) ...
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### Is it hotter in different places with the same air temperature?

A temperature is a temperature but the effect of that temperature is not always the same. Some things that add to our perception include sun intensity, wind, humidity, and simply what we are used to. ...
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