The International Date Line is where the date changes, not the boundary between night and day. There is no name for that boundary, because it always moves.
Surface Waves
The sun!
Approximately 5150 km (3,160 miles).
Roughly 2900 kilometers to the boundary between the mantle and the outer core which is a liquid.
divergent
surface wave
Surface Wave (APEX)
Gases cannot form a free surface on their own. However, gases do have a free surface at the boundary between gas and liquid, such as the free surface of the sea, or the boundary between the liquid of a soft drink and each carbon dioxide bubble rising in it.
mix
Basal Surface of Weathering is also known as the Weathering Front, which is the boundary between weathered and unweathered rocks.
Surface Waves
surface waves
surface waves
This is known as the phreatic surface or water table.
Thermal Layer
This is known as the phreatic surface or water table.
surface waves