Sweating through summers

Unlike my life in the old country where I experienced only two seasons--hot, and rainy--my life here in the Pacific Northwest is defined by four seasons.  The changes are gradual at first, and then dramatic enough for us to wonder when the season changed.

Summer begins on the longest day of the year--June 20th--and the weather is forecast to reach a high of 97 degrees on the 21st.

97?

It is only a matter of time before we begin to complain about the bright sun and the heat.  And, of course, I will lead that chant!

I have acclimated to the temperate conditions in this part of the world. Every year, as the temperature rises, I wonder how it can be possible for a boy who played outside under hot and humid conditions to become a wuss who cannot bear even the much lower temperatures.

During my visits to India, it is always a struggle within when it comes to having coffee in the afternoon.  Should I have a hot drink when it is warm all around, or have something cooler?

Of course, such a question never came up when I was young.  Hot coffee or masala tea on a hot afternoon was what we had.  Was it because we didn't have a fridge for the longest time?  Or, is it because it really helps drinking something hot on a hot day?

While having hot coffee on summer afternoons might sound strange, it is not stranger than people licking ice cream on cones while walking on cold winter evenings here in my adopted home.  So, if having ice cold stuff in winter is ok, is there any benefit in drinking hot coffee in the summer?

This has been a matter of scientific inquiry, too.

There are all sorts of receptors in all sorts of nerves, but the nerves in the tongue have a lot of one particular receptor that responds to heat. It's called the TRPV1 receptor, if anyone wants to know.

So when you eat or drink something hot, these receptors get that heat signal, and that tells the nerve to let the brain know what's going on.

When the brain gets the message "It's hot in here," it turns on the mechanism we have to cool ourselves off: sweating.

Yes, the hot drink makes you hotter ... but it does something else, too.

"The hot drink somehow has an effect on your systemic cooling mechanisms, which exceeds its actual effect in terms of heating your body."

Aha!

But, what if the conditions are also so humid that the sweat doesn't vaporize and cool the body but instead sticks around?

This is the nightmarish scenario that Kim Stanley Robinson describes in the opening chapters of Ministry for the Future.   Robinson emphasizes the wet-bulb temperature, which translates the effect of the thermometer reading after accounting for evaporative cooling.  This cooling does not happen at 100% relative humidity. 

So, if the temperatures are rising in the old country, with humidity levels the same as they were when I was a kid, then sweat as a cooling mechanism doesn't really work as it once did.  Instead, sweating adds to the misery.  As Wikipedia puts it, "Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of 32 °C (90 °F), equivalent to a heat index of 55 °C (130 °F)."

Here in the Pacific Northwest, the summer months are practically drought times, and the humidity levels drop.  While we never experience terrible wet-bulb temperatures, we begin sweating at the first report of forest fires, which are becoming more and more frequent.