The shady (usually poleward, or north in the Northern Hemisphere) side of a mountain. The term originated and is most often used in reference to mountains in the Alps. It is characterized by a lower t
imber line and snow line than the sunny side (the adret).
A radio noise burst associated with some flares. It has a U-shaped appearance in an intensity vs. frequency plot. The minimum intensity falls roughly between 500 and 2000 MHz. A U-burst is sometimes c
alled a Castelli U.