ET metamorphosis occurs:

• in snowpacks that are nearly isothermal or
• when the snowpack is deep

In weak temperature gradients (<10°C/m) sublimation typically moves mass from convex surfaces (points) to concave surfaces (hollows).

Snowflakes and decomposing precipitation particles.
Sources: Large crystals are from SnowCrystals.com.
Background photograph by E. Akitaya.

The compact snow grains that result from the snowflake erosion occupy much less space and result in the increasing density and stability/ strength of the snow pack.

During the rounding process the particles bond together by forming necks. Sintering is the process by which two particles weld together without a liquid present. Notice that there are bonds or "necks" between the rounded crystals in the right hand image.

Small rounded crystals

Well-rounded crystals with necking between them

QUESTION: Why is equi-temperature metamorphism referred to as "destructive"?

Click here for a complete desciption of equi-temperature metamorphism snow grain types.

Click here for more snowflake images.