Melting layer

From Glossary of Meteorology

melting layer

The altitude interval throughout which ice-phase precipitation melts as it descends.

The top of the melting layer is the melting level. The melting layer may be several hundred meters deep, reflecting the time it takes for all the hydrometeors to undergo the transition from solid to liquid phase. The temperature of the melting layer is typically 0°C or slightly warmer.
See bright band.