What are the biggest differences between Ocean World (Europa, Ganymede, Callosto, Titan, Enceladus, etc.) cryosphere (ice sheets) and Earth's glaciers and ice sheets?
Scale. Ocean World ice sheeets are thick. From 20-ish to 150 km thick. (Callisto and Ganymede maybe more )
Structure. Ocean world ice crust has two layers. Upper is cryogenic (100 K) and stiff. Lower is convective. And warmer, near melting point.
Pressure. Amazingly about same at deep part. Surface might be less. [1/2]
More differences of #OceanWorld ice.
Temperature. At top of many icy moons, the ice is waaay colder than Earth. 100 K on many worlds. The coldest on Earth is maybe 200 K. Cold ice is different. Harder, abd high thermal conductivity makes it harder to melt at a spot on surface (heat energy just conducted away.)
Formation. Ice sheets and glaciers are meteoric ice. Comes from snowfall. On Ocean Worlds (except some areas Enceladus is freeze down ice.
@TDDH That is a great question!
I don't know! But Imma gonna take a guess from some clues.
During snowball Earth, there were dropstones out in deep water. So that shows that glaciers were forming on land and dragging rocks out to deep ocean. That means that snowfall to glaciers was happening. Was not just ocean freeze down.
So while some ice shelf freeze down ice expanded, there was still a glacier story of snowfall.
Mike Malaska
CuriosityBot
berndandeweg