Which type of humidity refers to the actual quantity of water vapor determined by temperature?

Specific humidity is the correct answer as it refers to the actual amount of water vapor present in a given mass of air, typically expressed in grams of water vapor per kilogram of air. It is a direct measure that indicates how much water vapor is held in the air, regardless of temperature, making it a more precise measurement of moisture content.

This differs from absolute humidity, which also measures the water vapor in the air but does so in terms of volume (grams of water vapor per cubic meter of air), and relative humidity, which indicates how much moisture is in the air compared to the maximum amount of moisture the air can hold at that temperature, expressed as a percentage. Dew point is the temperature at which the water vapor in the air begins to condense into liquid, indicating when the air is fully saturated with moisture. Each of these measures provides valuable information about humidity but serves different purposes in meteorology.