Humid…it’s all relative

I just got back in from dinner…ugh, it was so humid…my hair has now frizzed. The dew point in Nashville is 68 degrees.  That is humid.

LISA MUGGY METER.png

It’s 82 degrees as I’m writing this (8pm), so that gives us a relative humidity of 63%.  But wait a minute, this afternoon at 1pm it was 91 degrees and the dew point was the same, 68 degrees, but the relative humidity was lower at 47%.

4-severe-storm-threat-2

 

Is it more humid now that it was this afternoon? The answer is “no”, the amount of moisture in the air hasn’t changed, but the temperature has, so the “relative humidity” is different.  You see relative humidity is the ratio of moisture in the air, relative to the temperature.  Warm air can hold more moisture than cooler air, so the relative humidity does tend to rise at night even though the amount of moisture in the air remains the same.

relative-humidity

With that said, when is the moisture content in the air going to be lower here in Middle Tennessee?  We will get some relief with dew points back in the 50s Monday, Tuesday and Wednesday of next week.

Until we get there, Thursday and Friday will remain hot and sticky with isolated afternoon thunderstorms.

An approaching front will bring a greater chance of rain on Saturday and Sunday and slightly lower temperatures.  We aren’t looking for a wash out this weekend.  Just plan for some on and off rain and thunderstorms.

wsmv-4day-forecast

After the front passes the slightly cooler and drier air mass will settle in for the beginning of next week.

I’ll have an update on Channel 4 News at 10pm.

posted 9pm

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About Lisa Spencer

Lisa Spencer is the chief meteorologist at WSMV Channel 4 Nashville. You can catch her weathercasts weekdays at 5pm, 6pm and 10pm.
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