Thoughts on heat, humidity, droughts and our future

I read today that a "heat dome" has settled in over the central US, covering about 1 million square miles. Some sort of upper atmosphere high pressure system that is moving v e r y slowly...

A short video I found on line has a nice graphic showing how the large, powerful heat "dome" deflects all other weather systems that are moving across the country. This is what leaves us with these hot, humid - but without rain - conditions and no relief for days on end.

It sounds like the system will break by Monday, but in the meantime, those with air conditioning are surely running it, and those without are probably spending a lot of time at the public library (or other cool public place).

I was surprised to read that humans actually tolerate heat quite well, provided we are able to sweat and have plenty of fluids. But, another important factor is that the sweat has to be able to evaporate - it is the evaporation that has a cooling effect on our bodies.

Unfortunately, when the heat is accompanied by high humidity, the air has little capacity for additional water, so that sweat doesn't readily evaporate. That means one is left hot and sweaty, but feeling no cooler. ugh.

Humidity comes in several forms from a scientific standpoint, and each one is calculated a bit differently: absolute humidity, relative humidity and specific humidity are all used. You can read the Wikipedia article for a thorough explanation of each. For we lay-people, the one that has the most relevance is relative humidity. RH is a measure of the amount of water vapor in the air relative to the maximum amount of water vapor that the air could hold without actually starting to rain.

RH is the factor used to calculate the "heat index", or the temperature it feels like to us when the humidity is high. For instance, when the weatherperson says "the temperature will be 93 today, but it will feel like 105," he or she is talking about the heat index that is adjusted for the relative humidity.

While reading about this weather phenomenon, I came across a 2004 article with information from the National Center for Atmospheric Research. The scientists had run some models to look at how weather systems are expected to shift as the climate changes due to global warming. Among their findings was that stationary high pressure domes that result in long-lasting heat waves will become more frequent over Europe and North America.

Some places, like Kansas and Nebraska, are predicting serious groundwater shortages this year as farmers are forced to irrigate crops that would otherwise wither and die from the lack of rain. An area can manage a drought year like this once in a while, but not several years in a row. China and Russia have suffered through record droughts in recent years, giving us some idea of what may be in store.

Seems about time we started figuring out a different system that will work with the available resources like water as well as the weather conditions that are coming. Not just in the US, but around the globe.

Too bad humidity doesn't water crops...