barometer
an instrument that measures atmospheric pressure
cirrus
a wispy white cloud (usually of fine ice crystals) at a high altitude (4 to 8 miles)
cumulonimbus
a dark cloud of great vertical extent charged with electricity; associated with thunderstorms
crystallize
cause to form crystals or assume crystalline form
rain gauge
gauge consisting of an instrument to measure the quantity of precipitation
wind vane
mechanical device attached to an elevated structure; rotates freely to show the direction of the wind
physical change
a change from one state (solid or liquid or gas) to another without a change in chemical composition
mixture
a collection containing a variety of sorts of things
