Weather Why's: Why the Dew Point Matters
Humid days continue in southern Minnesota today as dew points climbed into the low 70s. This week on Weather Why's, meteorologist Joshua Eckl explains what dew point really means.
Dew points in the summer months can be a bit of a sticky subject.However they are a key measurement meteorologist use in helping you prepare for your day ahead.
Dew point is the temperature that air would have to be cooled to in order for the air to be saturated with water vapor. In other words, it is the temperature at which an object, such as a blade of grass (dew) or a car windshield (frost), will become wet with water or ice from the air.
Think of it this way, higher dew points mean the more water vapor the atmosphere can hold. The more water vapor the atmosphere can hold the more humid it becomes. Often we refer to this by using a chart explaining the comfort level outside. Where less than 55 is dry and comfortable, 55 to 65 is sticky with muggy evenings, and anything above 65 is considered oppressive.
Meteorologist rely on dew points to help predict the weather. If the difference between the temperature and dew point are small, there is more moisture in the air and more likely hood for the development of fog, frost, and clouds.
One thing that is often miss understood about dew points or level of moisture in the air, is that moist air is actually less dense then dry air. So as dryer air moves through it helps lift the more saturated air, helping form clouds and even thunderstorms.
As summer months come to an end, dew points settle into a more comfortable stage. Not long after that temps dip near freezing and we see the effect of dew points in the form of frost.
I'm meteorologist Joshua Eckl, KEYC News 12, with this week's answer to your Weather Why's.