A cloud that forms in the rising branches of mountain waves and occupies the crests of the waves. The most distinctive are the sharp-edged, lens-, or almond-shaped lenticular clouds, but a variety of
stratocumulus, altocumulus, and cirrocumulus forms appear in both the main, vertically propagating waves and in the lee waves. See mountain wave, foehn cloud.
A nocturnal, thermally forced wind from the direction of the mountains, generated by cooling along the mountain slopes; a downvalley wind, or the nighttime downslope (katabatic) component of a mountai
n?plains wind system.
A snow water content sampler consisting of a hollow tube of steel or duralumin and having an internal diameter of 1.485 in. so that each inch of water in the sample weighs one ounce. This sampler is u
sed almost exclusively in sampling deep snow in the mountains of the western United States. Its design includes a cutting lip for penetrating ice layers in the snow, longitudinal slots for cleaning after a measurement, and accessory wrenches for assembling and driving. The tube is made in short sections with threaded couplings so that it can be disassembled for transportation.
Classification of the magnetic character of sunspots according to rules set forth by the Mount Wilson Observatory in California.
alpha (a). A unipolar sunspot group.
beta (B). A sunspot group having
both positive and negative magnetic polarities (bipolar), with a simple and distinct division between the polarities.
gamma (G). A complex active region in which the positive and negative polarities are so irregularly distributed as to prevent classification as a bipolar group.
beta-gamma (BG). A sunspot group that is bipolar but which is sufficiently complex that no single, continuous line can be drawn between spots of opposite polarities.
delta (D). A qualifier to magnetic class (see below) indicating that umbrae separated by less than 2 degrees within one penumbra have opposite polarity.
beta-delta (BD). A sunspot group of general beta magnetic classification but containing one (or more) delta spot(s).
beta-gamma-delta (BGD). A sunspot group of beta-gamma magnetic classification but containing one or more delta spot(s).
gamma-delta (GD). A sunspot group of gamma magnetic classification but containing one or more delta spot(s).