Depth hoares are large crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s occurring at the base of a snow

Snow

Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...

pack that form from when uprising water vapor

Vapor

A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....

 freezes

Freezing

Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....

 onto existing snow crystal. Depth hoares are sparkly large grains with facet

Facet

Facets are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure...

s that can be cup-shaped and that are up to 10 mm in diameter. Depth hoares are loose granules that run through fingers and that bond and adhere to each other poorly, highly increasing the risk for avalanches.

The formation of depth hoar in antarctic firn

Firn

Firn is partially-compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice...

can cause isotopic changes in the accumulating ice. This can influence analysis of ice cores in scientific research

External links

• The Avalanche Encyclopedia, extensive summary with animation of formation process