A phenomenon in which the shape of sunspots flattens as they approach the Sun's limb due to the solar rotation. More specifically, when a sunspot approaches the solar limbs the width of the penumbra,
relative to the umbra, on the side facing the center of the Sun seems to become narrower than on the side facing the limb. This phenomenon arises from a projection effect, and is due to a geometrical depression (the Wilson depression) in the layers of constant optical depth in sunspots.
A phenomenon in which the shape of sunspots flattens as they approach the Sun's limb due to the solar rotation. More specifically, when a sunspot approaches the solar limbs the width of the penumbra,
relative to the umbra, on the side facing the center of the Sun seems to become narrower than on the side facing the limb. This phenomenon arises from a projection effect, and is due to a geometrical depression (the Wilson depression) in the layers of constant optical depth in sunspots.
Snow lost to wind ablation on one part of the glacier surface is often re-deposited in more sheltered parts of the glacier surface, making no contribution to glacier-wide ablation.
Blowing snow or drifting snow. Windborne snow may be redistributed from one part of the glacier to another. It contributes to the glacier-wide mass balance only when it is carried across a lateral bou
ndary of the glacier, either inward or outward, or when it suffers sublimation instead of being redeposited.
Any device designed to obstruct wind flow and intended for protection against any ill effects of wind. Installations of this type include agricultural shelterbelts, snow fences, and rain-gauge wind sh
ields.