Strange air…

2006-11-26 09:23:57.000 – Jim Salge,  Observer

Mirages of Vermont…

The inversion continues. High pressure overhead continues to keep the summit of Mount Washington as the warmest spot in New Hampshire again this morning. Well, I guess that’s not entirely true, as our 4000 foot site on the ARVTP was nearly 50 degrees at daybreak. The duration of this clear, calm and stable air has been truly remarkable, as the summit has only been in the clouds once in the last 7 days, and usually the station sits in the clouds 60-70% of the time. And in November no less…our climatologically cloudiest month.

Some of the secondary effects within this weather system have been quite interesting as well. One thing that has stood out has been how dry the air is in absolute terms. Besides the sub 1% relative humidity that we saw yesterday morning, the dewpoint on the peak was -54F. That means that in order for dew (or frost) to form, you would have had to cool the air nearly 95 degrees to squeeze the water vapor out. A far cry from watching dew collect on the soda can this summer.

With the air at 6000ft remaining so dry, an absurd clarity to the air has allowed some of the most distant views I’ve seen up here. The Adirondacks are usually a real treat to see, visible only a few days each year, but we’ve been waving to Mount Marcy every day this shift thus far. The only haze that did creep into the white mountains this week was suppressed to elevations under 3500 feet by the inversion, and it allowed for some neat scenes like this one.

Lastly, the inversion has caused some neat optical effects in the atmosphere. The picture above shows the famous mesa’s of central Vermont. There are of course, no flat topped mountains in Vermont, and what you see in the picture is merely a mirage. The bottom of the inversion layer is acting like a mirror, reflecting and inverting the mountains creating the unusual scene seen here. For more information on that effect, you can click here!

Jim Salge,  Observer