If a weather report indicates that the relative humidity is 90%, what would happen if the temperature dropped?

Question

If a weather report indicates that the relative humidity is 90%, what would happen if the temperature dropped by ten degrees celcious?

Answer 1

All other factors remaining constant, the relative humidity would increase. Relative humidity refers to the amount of water dissolved in the air as a percentage of the total amount of water the air, at that temperature, can hold. The warmer the air, the greater its capacity to hold water. It rarely snows in Antartica because the average temperature is so low the air can only hold a very small amount of water.
Summing up; it is called RELATIVE humidity because the actual amount of water in the air does not alone determine the relative humidity. It is a function of the temperature of the air, ergo its capacity to hold water, as well.
As an aside: even at 100% relative humidity air can only hold a maximum of 4% water by weight.

Answer 2

If for example the temperature was 6°C and the dewpoint was 4°C, the relative humidity would be around 90%. In a stable airmass, the temperature will generally not fall below the dewpoint at night. If it does, you will get dew or frost forming along with fog patches. A drop of 10°C would be the result of a changing airmass would may have different properties such a changing dewpoint, wind speed, etc.

Answer 3

As the temperature dropped, the humidity would increase until it reached 100%. At this point, it would either become very foggy or else some other form of precipitation would develop.
The lower the air temperature, the more difficult it is for it to absorb and retain moisture from other sources.

Answer 4

From what I understand if the temperature reaches the dewpoint it will rain.

Answer 5

It probably would rain.