Why does higher dew point indicate more water vapour molecules in the air?
In: Physics
It’s a little bit the other way around. More water vapor in the air means the dew point is higher. This happens because warm air can hold more water vapor than cold air, when the air cools off, the excess water “overflows” and forms dew (or frost if it is below freezing).
You’ll also see this with the relative humidity percentage. 100% humidity means the air can’t hold anymore water, so even a tiny bit colder and it will form dew. Think of it like the container shrinking but the water has to go somewhere. At 50% humidity the air can hold twice as much water as is currently there, but if the air cools off it increases the relative humidity. In this analogy the container is shrinking and so it is more full with the same amount of water. It can shrink as it cools off further until you hit 100% humidity and it overflows, that temperature where it overflows is the dew point.
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