I see on weather apps that for a given temperature and humidity, the dew point is x. I looked into it and I learned that the the dew point is the temperature that air must be cooled to in order for dew to form. I also saw that the formula for the dew point (Td) is Td = T-((100-RH)/5) there T is the observed temperature and RH is the relative humidity.
If this formula is accurate, then in my mind, it means that Td would be recalculated whenever T drops, thus making the dew point impossible to reach.
For example: T = 26 and RH = 60% then Td = 18. If the temperature then drops to 18, we have T = 18 and RH = 60%, so Td = 10, and so on, meaning that the dew point for a given moment is never reached…
Where am I going wrong?
In: 3
Hotter air can hold more water, and colder air holds less water. If the amount of water in the air doesn’t change, then as the temperature goes down, Relative Humidity actually goes up. That’s why it’s called relative humidity. As opposed to something like “oz of water per cubic foot” or something which is absolute number.
The dew point is the point where RH would exceed 100%. That’s not possible, and the water in the air turns back into water.
This is why a cold beverage (beer, soda, etc) from a refrigerator gets wet on its own by magic. The beverage is colder than the dew point, so the humidity in the air turns into water on the can/bottle itself.
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