The air is holding as much water as it can. It will frequently be heavy fog or raining.
Since it's usually snowing, the relative humidity is near 100%.
100%.
100%
100%.
Relative humidity is 100% of water vapor in the air. When that happens dew forms.
When a parcel of air is saturated with water vapor the relative humidity of that parcel of air is 100%.
Relative humidity rarely reaches 100% humidity when air is polluted. This is do to emissions of carbon dioxide and sulfates, and is known as haze.
It is raining
100%
Near 100%.
100%
That would be "dewpoint"...When the air temperature falls to the dewpoint (or dewpoint rises to the air temperature), then you have 100% relative humidity.