You hear it in every forecast. But what is humidity, and why does it make Houston summers so brutal?
What is humidity?
I know in Houston, we hear the term humidity which is used to correlate to how muggy it may feel outside. But what actually is humidity and what does it represent? Humidity is the measurement of water vapor in the atmosphere. There are different ways to measure humidity.
Absolute humidity
Absolute humidity represents the amount of water vapor in a given volume of air. Often measured as grams per meter cubed, absolute humidity is not dependent on temperature change. This is due to the fact that the amount of water vapor in the air does not change whether hot or cold.
Relative humidity
Relative humidity is the most common form of humidity used when talking about how muggy it is outside and the heat index. Relative humidity represents the percentage of water vapor in the air compared to the maximum amount it can hold at a specific temperature.
Dew point
Dew point is the temperature at which the air must be cooled to reach saturation of 100% humidity. In context, the dew point can never be higher than the air temperature. The dew point can give us a better idea of how humid it is than relative humidity. Why is that? Let’s give an example. Let’s say the temperature is 30 degrees and the dewpoint of 30 degrees as well. The relative humidity is 100%. Now let’s look at another example. Let’s say the air temperature is 90 degrees and the dew point is sitting at 65. The relative humidity will then be 44%.
Which is a better measurement of humidity?
Dew point is an overall better measurement of how humid and dry the air really feels. From the examples before, it is possible to have a high relative humidity but with low dewpoints and higher dew points with low relative humidity. So, the next time you want to know how humid or dry it is outside, check those dewpoints on your KPRC 2 Storm Tracker app.