Wednesday, July 11, 2012

How Hot Was It? Really?

Kevin Myatt writes weather for a Roanoke daily paper and website and has gained quite a reputation for his insightful look at what's happening outside and why.

I posed a few questions to him this morning about why the weather service and I don't see eye to eye on just how hot it was last week and he had some good answers.

Here they are:

"The reason the weather service sets up official temperature sites like the one at Roanoke Regional Airport is to create a uniform system of measurement so that data is apples to apples, oranges to oranges as much as is possible from site to site. So every official thermometer is 6 feet high and enclosed in a ventilated box to protect it from the sun while allowing air to circulate within.

"I'm guessing your thermometer doesn't meet these criteria -- the one at my house doesn't either, and it topped 100 each day as well and reached as high as 109. Things like how sun reflects off various surfaces, heat from buildings, wind circulation patterns around structures can affect individual thermometer readings several degrees even within a very small area.
"I suspect you are correct about the asphalt and development in your part of town being a factor. The National Weather Service requires weather measuring instruments to be a certain distance from any streets or buildings or the readings are not considered official.

"And there are certainly microclimates, too -- they also show up in the winter when the snow starts sticking faster at one location than another not far away. In our one decent snow last winter, I had 2 more inches than the official 5.5, mainly because of slightly higher elevation and being a little colder, so the snow started sticking faster.

"I suspect home thermometers in 1983 and 1977 were showing higher temperatures than official readings as well."

What all this means to me is that the weather service is giving us a general guideline and that the guideline is not always the absolute truth, except in that place and at that box. I know when I walk onto my porch and it's 112 degrees--not 104--my body reacts differently. But this is our system and it's one that's worked for a long time. It's just that this summer, it's hotter than that.


1 comment:

  1. yah it is a very hot time.we can know Weather by many Weather thermometers .it is a important thing t o know weather.