When it is raining on the ground, how far up into the atmosphere does this rain extend?

Usually up to the "freezing level", where the temperature has decreased to below 0┬░ C (over the tropics, that occurs at about 5000 meters; over Los Angeles, it fluctuates between 2000 and 4000 meters in winter, and between 4000 and 5000 meters in summer). In different types of rain, there can be frozen water such as hail mixed with the rain below the freezing level, and/or "super-cooled" liquid drops above it.

In most storms, the GPM DPR is very good at detecting the freezing level. The GPM DPR has separate channels to identify frozen, melting, and liquid particles, thereby providing very detailed information about the evaporative cooling and/or condensational heating released into the atmosphere by rainstorms.