I am very confused about the definition for "humidity". Allow me to an example.?

Question

I just read this statement in an article about the flu: "The flu virus survives for longer periods indoors in winter because the relative humidity of indoor air is very low in comparison to the outside air".

Does this mean that the air inside of a house in the winter is lighter, less heavy, then the air outside? Whenever I think of humidity or the humidity levels being heavy, I always think of the air as being heavy, warm, almost more liquid, as with water droplets. For me, light humidity means air which is fresh, light, not compressed. Sorry to bog this question down. Also for me, when it rains, as in a low-front, I always think that the air will become muggy, again, thick, heavy, compressed.

Tell me if I am right, on the right track, or need to have a drink and go back to school?

Please PLEASE PLEASE PLEASE PLEASE DO...NOT...write back to me with some long, drawn out TECHNICAL SCIENTIFICAL answer..I will simply ignore it. I need some down to earth, Layman jargon here. Thank you, truly!

Answer 1

The problem is you are asking about 10 questions.

Relative humidity is how much moisture the air can hold compared to the maximum it can hold. If the RH is 90%, then it has 90% of the maximum, and will feel very heavy and damp.

When you warm up air, like going from outdoors to indoors in the winter, then the air can hold more moisture, so the RH goes down, and it feels dry.

If you go in the other direction, from warm to cold, the RH goes down, and if the air already had a lot of moisture in it, you may exceed the RH, and the water condenses out. That is why you get steam when you exhale in the winter -- the air starts out warm and moist, then has to cool off, exceeding the RH, and the excess condenses out as water or ice.

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Answer 2

Typically, indoor air and outdoor air in winter have about the same percentage water vapour content.  However, the indoor air is warmer, and warm air can hold more water vapour than cold air.

So what is called the relative humidity, water vapour content as a fraction of the maximum possible water vapour content before the water condenses out, is lower. It is the relative humidity that counts.

Einstein is supposed to have said that every scientific problem should be made as simple as possible, and no simpler.  I have tried to do this here.  Hope it helps.

Answer 3

Humidity basically means how much water in the form of water vapour is in the air. High humidity means a lot of moisture in the air giving the feeling of heaviness. Low humidity means the air is very dry giving a light feeling. The most common way of measuring humidity is the term relative humidity (RH). 100% RH means the air is full or saturated and it feels very damp. In high humidity the water vapour condenses on our skin and in bathrooms it condenses on mirrors, shower cubicles, tiled walls etc. A 50% RH means it is only half full 10% RH would very dry air. As the temperature of the air increases the amount of moisture it can carry increases and vice versa the colder it is the less moisture the air can carry. In winter the outside temperature is usually lower than the temperature inside a house so the RH outside is higher (more damp) than inside. The article would suggest the flu virus survives better in a dry atmosphere. I hope this is simple enough but you may wish to check out the website below.

Answer 4

Humid air is lighter than dry air, that is why thunderstorms form.

Just as liquid water is lighter than liquid air.

You have to compare like with like, you cannot compare gaseous air with liquid water.

Answer 5

As warm humid air is cooled (without losing moisture) the dewpoint temperature is reached (where dew begins to form) and any additional cooling will cause more condensation to form, also lowering the dewpoint.  At the dewpoint, there is 100% relative humidity because the air holds exactly as much moisture (water vapor) as it can at that temperature.  If the air is then heated it can hold more moisture than it has and the relative humidity will be less than 100%.  A relative humidity of 100% feels muggy because sweat can not evaporate to cool the skin.  A relative humidity of 50% may feel comfortable whereas 20% will feel too dry.

Air outside on a cold day may be at the dewpoint (especially if there is wet snow) and when the air enters a warm house through drafts, etc. and heats up it will likely have a very low relative humidity and will feel very dry.  That is why many homes must use humidifiers (but only in the winter).