When water molecules are warmed up - usually by heat energy from the sun -  they receive enough energy to change from liquid to gas.
(water molecules; are warmed; T:up - usually; by heat energy) (they; receive; enough energy to change from liquid to gas; T:When water molecules are warmed up - usually by heat energy from the sun)
water molecules they
are warmed receive
T:up - usually by heat energy
enough energy to change from liquid to gas T:When water molecules are warmed up - usually by heat energy from the sun