Answer:
Evaporation and gravity cause water to move through the water cycle.
Step-by-step explanation:
Evaporation turns liquid water into a gas, and brings it up into the atmosphere, where the gas condenses into frozen water molecules, which stick to each other. When a clump of water molecules gets too heavy, gravity pulls them down to the surface as precipitation. Depending on the temperature, the frozen water droplets may melt, or stay frozen.
Gravity brings precipitation to the ground.
Water has to heat up from high temperature, from either the sun or another heat source, to change the form from gas to liquid.
Water vapor must get to a certain temperature of cold to freeze, causing it to condense from a gas to liquid.
Thermal energy causes evaporation of water, which allows the water to be reprecipitated once again.