If the temperature within the clouds is very low, the water drops freeze to form crystals of ice that tend to stick together.
(the temperature within the clouds; is; very low) (the water; drops freeze; to form crystals of ice) (crystals of ice; tend; to stick together) (crystals of ice; to stick together; )
the temperature within the clouds the water crystals of ice crystals of ice
is drops freeze tend to stick together
very low
to form crystals of ice
to stick together