Tuesday, September 20, 2011

Microclimates

When nights are longer, winds are light, and the skies are clear we often see larger local differences of temperatures at night, and particularly at daybreak when temperatures are coldest.    Consider the temperatures around Puget Sound this morning at 7 AM (sunrise was 6:53 AM):

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Quite a range!  Temperatures varied from 37F at Shelton to 52F near the water in Seattle--15F!.   Clearly, being near the water helped keep you warm (temps of Puget Sound were in the lower 50s) and there was substantial cooling as you moved inland.  And remember these are air temperatures at roughly 5-6 feet--the temperatures of some of the ground surfaces could have been lower.   Perhaps even some frost near Shelton!

During the late fall, when the water is still near 50F and the interior drops into the teens, we can have far larger temperature differences.

But proximity to water is only one cause of temperature variations.   The urban centers tend to be warmer (the heat island effect) due to the release of heat by concrete and the multitude of heat sources in a city.

And then there are terrain effects.  Cool air tends to flow into valleys and low spots, and thus they are cooler...sometimes by 5-8 F compared to surround hills or ridges.  If you have a car thermometer you can see this effect as you drive.   Or if you are crazy like me, you might walk around a hilly neighborhood with a digital thermometer.

You see why TV weathercasters show multiple temperatures on the news--they have to---temperatures are too variable around here.

What about daytime high temperatures?  Here are the temps at 3 PM this afternoon.
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Mid-50s near the water to mid 70s inland...even as high as 81F at Kent.  Roughly 25F variation.  Temperatures of course decline if you go high enough, since in generally temperature decreases with elevation:  thus, temperatures are less in the Cascades.

You got to love living in an area whether you can choose your climate with a few mile drive. 

Of course, there are even smaller-scale microclimates:  the differences between an eastward or westward facing slope, north or south side of your home, shady versus sunny plots, and more.  I learned from experience where I should not plant my tomatoes.

Friday, September 30th, I will participate in a meet-and-greet with two excellent Seattle School board candidates: Marty McLaren and Sharon Peaslee at Puget Ridge Cohousing Assn, 7020 18th SW (north of SW Myrtle) from 6-8 p.m.  Refreshments of course.

Dog Update:  My little cockapoo is still on the loose...if you are in Seattle and see her (see below), let me know...thanks...cliff

2 comments:

Westside guy said...

I love reading your stuff, Cliff - but the new image viewer that this post uses makes it darn near impossible to get at a larger version of the image.

Lorac said...

would you please put temperatures into degree C as well? degree F is so crazy (stupid)