Complex sentence: In contrast to temperature control at high latitudes, the isotopic composition of precipitation in mainly influenced by rainfall amount (negative correlation) in the tropics, and the "amount effect" is also observed for summer precipitation in the subtropics.
Split into simpler sentences: In contrast to temperature control at high latitudes, the isotopic composition of precipitation in the tropics is mainly influenced by rainfall amount (negative correlation). This "amount effect" is also observed for summer precipitation in the subtropics.