Sunday, June 5, 2011

Water in the Air


Hot humid summer weather came to New Jersey for a while last week.

Monday, Memorial Day, I went out to run at 05:00. It would be too hot later in the day. I wake up then anyhow.

At that hour, this time of year, there's light in the sky. The local bird population perform a rousing morning chorus, as if spring will never end. At that hour, that day, it was reasonably cool, but only a few blocks of running told me how much humidity was in the air. Ugh.

My usual plan lately is:— Walk a half mile to warm up. Run one. Walk two blocks. Run another. Walk up a steep hill (it stretches the legs) and three blocks more. Run a half. Home. I walk a block past home and back to cool down.

The first mile run was tough. I know enough to go slower, but it was a struggle. In the second mile, halfway through, I took a walking break for a block. But then in the second half I did manage a small uphill. I was damn tired but I was not feeling dizzy or faint.

I always think about things while I'm out.

This day I wanted to know what on earth humidity was doing to me.

I tried to be in touch with my body. I wanted to feel what it was telling me. Then I would gain insight. I would be at one with myself. I sensed that my body was telling me, You idiot, why are you running? But I don't listen to that stuff.

Mock strawberry.

Here is the first Google hit I got later, and it's a good one. See the sections 'Account for Heat' and 'Heat Alert!'. He blames it on poor evaporation, which causes heat buildup in the body. That was one of the things I was thinking of.

I was also thinking about how the air feels heavy when it's humid. It's like pushing through it, isn't it? And I was wondering to what extent water vapor replaces oxygen, and whether I was tired because I was actually getting less oxygen per breath.

A little research told me that water vapor does displace oxygen, but weirdly enough it makes the air lighter per cubic unit. Helen told me the same thing later. I guess what we feel, when we think it's heavier, is really the fatigue of not cooling down normally as we move. We'd get the same feeling if the air was heavier.

Should I be amused or sad about seeing so many web forums where runners wonder why humidity is higher in the cool of the morning? Why? Oh, maybe it's because that's why they call it relative humidity? I am not a scientist and I know that.

But it raises a puzzling question. I like running at dawn because the temperature is at its lowest point of the day (usually), but by doing that I'm also putting myself in the highest relative humidity (usually). What's the tradeoff? Later in the day, I'd be able to cool off better from evaporation, but I'd also need to cool off better, since it's warmer out. Which way should I go, if I could run at either time?

It's moot, since I can only run at one time, but inquirin' minds want to know. They want to know a lot of things. But, back to our story.

View from the house. Compare to this.

When I got home I sat down on the front steps. It was a little cooler outside than in. (We turn off the living room air conditioner overnight.)

I took off my shoes and sat there and considered the world. The front garden looks great this time of year. Helen has put out all the potted plants, and we've got flowers on them and on the ground plants too. It's pretty lush.

Fact is I was too worn out to feel like moving.

My head was empty of words. I was just gazing at the riot of leaves and flowers. Nature's beauty.

There was a little flash of light just at the edge of my vision. Then I saw another in focus. A lightning bug! And it wasn't even June yet. Cool.

After some minutes a very welcome cool breeze stirred and stopped. Another breeze came. The plants moved here and there as the little breezes touched them.

Up in the trees the leaves showed their darker and lighter sides as they fluttered.

And I noticed the colors of the garden were becoming less bright.

In the sky to the south there was now forming a great grey mass of cloud. The breeze became more insistent, and cooler.

I noticed mosquitos pecking at my legs. Stupid nature. Just when I was feeling it. Just when I was communing with the world. Inside I went.

About five minutes inside, when— lightning flashed!— thunder shook the house! And rain started pounding on the house, a booming noise from all the open windows.

I had dodged that bullet by fifteen minutes.

The cold rain would have felt good, of course, but I don't want to be running in a lightning storm. I got caught in one once, when I was a mile and a half from home. It's an uncomfortable feeling whether you pass under open sky or under trees, wondering which is worse.

I cleaned up and put on regular clothes and flopped on the couch for an hour.

South side front garden. All three photos were taken at 06:00 Thursday.

When I went out later to get bagels, I could see twigs and tree seeds all over the street. The usual detritus. It had been a fine demonstration of the inevitable result of water vapor and cooling air.

Was the humidity any less then, an hour or so later? It didn't seem to be. It felt as if all the moisture released in the rain had been absorbed back into the warmer air of day, resetting the trigger for another round.

When Helen got up she looked out and asked, Did it rain this morning?



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