Ernesto and the sundogs…
2006-09-02 14:46:45.000 – Jim Salge, Observer
Thus far, Ernesto has behaved as forecasted in the White Mountains, leaving summits mainly free of fog with a high overcast. We still expect these clouds to lower and thicken, putting the peak back into the fog, and with a chance of rain moving in overnight and for tomorrow.
Until the rain arrives, the summit crew will likely continue to enjoy one of the many spectacular skyscape phenomena that usually precedes tropical systems. As background, I must state a rather surprising fact. The very tops of tropical systems, those that typically are blown well ahead of an advancing storm, are made up almost entirely of ice crystals. When the sun filters through these high clouds, the diffraction of light through these crystals can give some rather interesting optical effects.
The picture at right shows one such effect, called a sundog, which is typically found on either, or both sides of the sun in such conditions. Sundogs were in the sky most of the afternoon yesterday, as well as a number of other halos and arcs.
These are formed under the same principals as the ring around the moon forewarning of snow in winter, yesterday they were warning of Ernesto…showing there’s some truth to the old New England weather folklore!
Jim Salge, Observer