It’s not the heat, it’s the humidity! Why do we feel tired when the humidity is high?
It has to do with our built-in air conditioning: sweating — sort of.
When the air temperature and dew point temperature are close to the same, it means the air can’t hold any more invisible water (gas) in the air at that temperature and pressure. It’s like a sponge that is filled with water, we say it’s “saturated.” At this point, we start to see condensation or dew form, like a sponge dripping.
WHY IS THUNDER LOUDER IN THE MORNING?
Dew point temperatures below 60° are considered comfortable. Above 65°, we say it’s humid. Thursday’s dew points are forecasted to be in the mid-70s — that’s oppressive. Temperatures in the upper 80s with those dew points will make it feel more like the upper 90s.
It’s not sweating that keeps our internal temperature constant. It’s the evaporation of sweat that cools us. When the air around us has a high moisture content, we can’t do that as efficiently, and it leaves us feeling lethargic and tired.
LESS SUNLIGHT MEANS COOLER WEATHER FOR FALL
So how does evaporating sweat cool us? When liquid water (sweat) evaporates, heat is absorbed in the process. Heat is absorbed as the evaporated sweat moves away from us, the heat also goes with it. The net effect is cooling. When the air is dry, this works beautifully. But when the air is saturated, not so much. Stay cool!