Question

how much humidity is required to convert the water vapour into water?

(need short answer)​

Answer 1

At -40 °C (-40 °F), however, it can hold no more than 0.2 percent. When a volume of air at a given temperature holds the maximum amount of water vapour, the air is said to be saturated. Relative humidity is the water-vapour content of the air relative to its content at saturation.

Answer 2

the humidity required to convert the water vapour into water is 40°c