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Saturday, June 11, 2011

Keeping a weather eye (Part II)

I had not intended to write a follow-on to my previous post on weather.  However, in my research for my hike to Hossick Lake this Labor Day weekend I was interested to know what kind of temperatures to expect at 12,000 feet above sea level.  The technical term for the difference of temperature to expect at varying elevations is called Lapse Rate.  Like most things in science it's not an exact science, just a useful guideline on what to expect.

Lapse Rate
6.5 degree Celsius per 1,000meters
3.57 degree Fahrenheit per 1,000feet 

Now, my first attempt at this I found a lapse rate to determine the expected temperature difference of 6.5 degrees Celsius per 1,000.  What I didnt take into account was the all important "m" at the end of the 1,000.  Had I not noticed this my packing list would have been drastically different and for the most part useless. 

For an example I will show you the difference in calculations when you misread/misjudge/etc the specifics.  As I stated earlier I will be hiking to Hossick Lake in Colorado this September.  Unfortunately there's not an average temperature for Hossick Lake so I started with the closest city, Pagosa Springs Colorado.  The average temp for Pagosa Springs in September shows as an average high of 74.3f and low of 36.6f.  If we take these numbers and use what I thought was the correct lapse rate and do the standard conversions from Farhenheit to Celsius and back again here's what I got:

7.2k ft (Pagosa Springs) 74.3 / 36.6F or 23.5 / 2.5C
8.2k ft (Trail head)          61.7 / 23.9F or 16.5 / -4.5C
12k ft  (Hossick Lake)    11.3 / -26.5F or -11.5 / -32.5C

As you can see that would be what I would consider suicidal for anyone that isn't an experienced mountaineer.... Which I am not.  With those temperatures I would have needed some serious snivel gear.  So now that we have that scare out of the way let's look at what the actual lapse rate would be....

7.2k ft 74.3 / 36.6F
8.2k ft 70.8 / 33.1F
12k  ft 56.8 / 19.1F

Using the right formula makes a world of difference!  So now instead of packing a lot of heavy cold weather gear I can now expect temperatures that will be more suitable to recreational hiking.

If I haven't stated it before or if it's not been painfully evident yet let me say it now.  I am not a professional outdoorsman nor would I consider myself an expert.  Please do not take what I put in the blog as the gospel truth.  Always, always, always do your own research prior to going out and enjoying the great outdoors.  ALL THE GEAR IN THE WORLD WILL NOT SAVE YOUR LIFE IF YOU DO NOT KNOW HOW TO USE IT.