Monday, May 27, 2013

Cold, this Morning.

Not here, but up North.  It seems that there's a frost warning out for portions of the Northeast.  I wonder if brother David got any snow up in Vermont?

However, I did learn something from reading the article.  Did you know that temperature forecasts are based on eye-level?  I had no idea.
"Temperature forecasts are made for eye-level. However, temperatures near the ground on clear, calm nights can be 5 to 10 degrees lower for several hours, especially around and just prior to sunrise," Sosnowski continued.
So, Milady asks, "Who's eye level?  If the forecaster is 6'2", and I stand 5'2", whose eye level are we using?  Good question, Milady!

2 comments:

Rivrdog said...

The only eye level referred to in weather lore is for growing corn, which should be as high as an elephant's eye when fully mature.

I believe the eye level you have referred to is in NOAA's Instruction 10-1302 (Oct 4, 2005) for siting a weather observation station. 4 to 6 feet for the air intake of a remote sensor. Wind readings are supposed to be taken 33 feet (10 meters) off the ground.

The science behind this air temperature height requirement is all about cold-air pooling, which, as you suggest, can be extreme in a very short air-column.

Cybrludite said...

I recall there being a similar effect when measuring fallout. A couple feet of air will block alpha particles, so what might look safe from a gieger counter probe held at about shoulder-height by an adult could be very bad indeed for young-uns.