Geography 120 Ch. 7

gravity and frictional drag create a balance called terminal velocity. a falling object no longer has an acceleration because gravity is balanced by friction. so in order for a rain drop to fall and overcome terminal velocity it must be kinda large.

generates precipitation. begins with large droplets with high terminal velocities. the collector droplets collide with smaller droplets. compressed air forces the smaller droplets outside. and the collector drops capture the larger cloud drops.

tends to be very high because most of the droplets are coalessed into the collector drop and are unable to escape.

saturation vapor pressure of ice is less than super cooled water. when both are present, the super cooled water will be deposited onto the ice because the ice has a lower pressure causing the ice crystals to grow rapidly. the falling of the ice crystals and water creates riming and aggregation.

when ice crystals fall through a cloud and collide with supercooled droplets, the liquid water freezes onto them.

the joining of two ice crystals to form a single larger ice crystal.

results from the burgeron process, riming and aggregation.

always associated with warm clouds.

ice crystals that undergo extensive riming. falls to ground or provides nucleus for hail

concentric layers of ice build around graupel. repeated process of graupel being forced back up by updrafts and more ice forming around it. great plains has the highest frequency of hail events.

• begins as ice crystals which melt
• into rain through a mid-level inversion before solidifying in colder, near
• surface air

similar to sleet but the drops do not sollidify before hitting the surface.