Monday, June 13, 2011

Microclimates & Rain Shadows

I don't know of any other area where you can see Microclimates and experience Rain shadows more easily than the Pacific Northwest.

A microclimate is basically an area that has a distinctly different climate from areas nearby.  For example - where we stayed at Deception Pass - the climate there averages 14" of rain per year - but very close nearby the rain averages 45-200" per year.   That's quite a difference in rain (and sunshine)!  Deception Pass has its own Microclimate vs the surrounding areas.

The reason for this Microclimate is that Deception Pass in in the Rain Shadow of the Olympic Mountains.

That brings me to Rain Shadows.

When moist air is pushed over a mountain range - as it rises, it looses pressure and cools.  Cooler air cannot hold as much moisture as warm air  (think warm humid tropical air vs cold dry arctic air).

When the air cools, the moisture in it condenses, forms clouds, and falls out as rain or snow.

Then as that air (now minus much of its moisture) spills over the top of the mountain range and rushes down the other side, it is compressed due to greater pressure (think of your ears popping in an airplane as you climb or descend).  As it is compressed it is warmed...  Warm air holds more moisture so the rain stops, the clouds disappear.

You are now on the downwind side of the mountain range.  You are on the "dry" side of the mountains or you are "in the rain showdow" of the mountains.

This rain shadow is found many places.  The Sierra Nevada Mountains in California for instance are lush on one side, and Death Valley is on the other.  The Northern Cascades of Washington of present a solid wall of mountains that the moist air pushed off of the Pacific must be pushed over.

On the west side of the mountains you are in Moist Rain Forests.  The temps are 50's-60's, all the trees and ground is covered with moss.  It is cloudy cool and damp.  We lived in those forests for the last week or so.

Here are a few shots on the West side.

In a short 30 miles or so, you climb over the spine of the Cascades and once on the other side you are on the dry side of the mountains.  As soon as you start down from the pass, you notice the difference in the trees, the underbrush, the absence of moss.   

The change is quite dramatic.  
Today we made the change.  
In the morning it was damp and lush.  
I told Kate before we left, that in the afternoon we would be in an  entirely different climate.

Here are some photos of the East side

In the Rain Shadow of the Cascades

Tonight we settled at Curlew Lake State Park in Washington.
It is a very pretty and quiet off the beaten trail type of spot.
Great  Broadband & Satellite TV Reception too!

Tomorrow we continue the journey east.  Not sure where we will end up.

Glacier National Park on Weds.

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