lec 17 Flashcards
what allows for condensation nd cloud formation in the atmos
condensation nulcei
what is the typcal radius of a cloud droplet?
10 microns
terminal velocity
when the gravitational force upon an object is equal to the object’s drag. this is the fastest it will go
why dont we get rain every time clouds form
it depens on the size of the droplets formed. In many cases the droplet are so small that upward drafts in the atmos are greater than the terminal velocity of the drop. this keeps it up!
what is the updraft strength associated with a cumulonimbus cloud
10 m/s
what is required for a drop to fall from a cloud
the drop need to be large enough to have a terminal velocity larger than the updraft
how do drops grow
via collisions and coalescence with other rain drops.
do raindrops only form from condensation nuclei?
no. drops can form as a byproduct of droplet growth. during collision, drops grow to be very large and unstable. while falling a single large drop may split into 2 drops.
what is the Bergeron process?
the formation of ice crystals in clouds. it is most common outside of tropical regions bc clouds are at an altitude below freezing.
ice crystals cause evaporation of near by droplets, to which they absorb the vapor to grow
how do ice crystals form
via supercooled water attaching to ice nuclei
why do ice particles form more quickly than droplets?
bc the saturation lvl over ice (in below 0 conditions) is much lower than that over water . this explains why the bergeron process is the domination precipitation formation method, excluding topical regions
what is the mechanism of raindrop collision-coalescence
larger rain drops fall first, and will absorb or collect smaller rain drops on thier way down
