Moisture in the air can build storms, but also has the power to make us sweat. Years ago, hurricane Bonnie pounded my former home town on the coast with strong rain and wind. Temperatures were in the mid-80’s and humidity was very high. Soon after the sky cleared, though, local storm clouds began to build. After a short break, the days following the hurricane were filled with thunderstorms.
The culprit was moisture in the atmosphere. It’s a bit like gasoline. You put 16 gallons of the stuff in your tank. But it won’t make the car go while it’s a liquid. It has to be evaporated into a gas to burn in the engine and turn the wheels. Liquid water in a lake, river, or ocean won’t build storms. But once it evaporates and joins the atmosphere as an invisible gas, it’s a big source of energy. The hurricane had brought it, and local storms were the result in the aftermath.
When this moisture saturates the air and starts to re-condense into a haze, we have the well-known high humidity of Southern evenings. This time of the year, there tends to be a high pressure cell sitting offshore, between Bermuda and the Caribbean Islands. It slowly rotates clockwise, funneling air into Georgia. This comes with lots of moisture because it’s from a warm ocean surface. In Hall County, the ground is already hot from the sunlight. Warm, moist air arrives from the ocean. This isn’t a refreshing sea breeze. It’s muggy, stifling air, moving very slowly.
Gazillions of tiny water drops create haze. The air is holding all the water it can carry, which means high relative humidity and little if any evaporation. “High dew point” means the same thing – it takes only a little cooling for that water vapor to condense back into liquid form.
Unfortunately, our body air conditioning is of the evaporative kind. We have to perspire, or evaporate, moisture from the body to cool down. At high relative humidity, though, there’s little evaporation to provide cooling. Instead, we “sweat” and get our clothing soaked.
People complain about the humidity. But others find it preferable to desert conditions, where outside work in the dry heat can require drinking 5 gallons of water a day. We can get by with carrying a water bottle around, not a water tank.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.