PITTSBURGH (KDKA) — Many people around Pittsburgh are used to using “relative humidity” to determine how muggy it may, or may not, feel.
Using relative humidity is not the best way to do it.
While many people are familiar with relative humidity, it is just that; relative. It tells you how close the atmosphere is to saturation.
You can have 100% humidity when it is 50 degrees. You will still be comfortable, even though the atmosphere can’t hold onto any more moisture (this is when fog forms).
Another example: if the temperature is 85 and the dew point is 70, that gives you a relative humidity of 61%.
It is super humid, and you can tell that with a dew point that high, but the relative humidity is lower than the first example.
I am actually not sure why people started using relative humidity as a descriptor of comfort because, from a scientific standpoint, it is silly, but that is neither here nor there.
Now to dew points.
Dew points are the temperature at below which water droplets begin to condense and dew can form. The higher the dew point, the more moisture there is in the air. That moisture is what determines how comfortable you are, in respects to humidity.
Whenever your dew points are in the 40s and 50s, it is comfortable, humidity-wise.
When your dew points touch the low 60s, you start to feel the heavy air a little bit.
When dew points touch the mid to upper 60s is starts feeling muggy.
When your dew points are in the 70s it feels like a tropical rain forest.
On the reverse end, when dew points are in the 30s or below, grab the lip balm and lotion, because you will need it.
All these numbers stand alone and are not relative to anything else, so If you learn these numbers, you will have a far better system to determine comfort.
It may not be the “old way” you’re used to, but it is better.