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processes that would be relevant in a warm stratus cloud
Coalescence and Collision
processes could happen in the mixed phase region of a cumulonimbus cloud?
Accretion, Collision, and Aggregation
refers to two ice crystals merging together.
aggregation
efers to two particles, whether liquid or ice, hitting each other, but not necessarily sticking together.
collision
What type of precipitation falls through cold air (<0°C), then a melting layer, then a shallow freezing layer, hitting the ground without having time to refreeze?
freezing rain
type of precipitation results from numerous rounds of accretion, growing in size, until it is heavy enough to fall through the updraft?
hail
type of precipitation falls through cold air (<0°C) the entire time and reaches the ground as ice?
snow
type of precipitation falls through warm air and reaches the ground as liquid water?
rain
What is hail size directly correlated with?
updraft strength
What is the beginning reflectivity level commonly used to indicate the possibility of hail within a thunderstorm?
what color is hail when the hailstone is in abovee freezing temps?
clear
what color is hail when its in below freezing temps
opaque
what size hail is considered severe?
greater than 1 inch
what are some seeding agents?
Dry ice, silver iodide, and any chemical structure that is similar to ice.
what is cloud seeding
using any seeding material to use more of the supercooled water and helps it become large enough to fall to the ground.
natural cloud seeding
cirrus clouds drop ice crystals, seeding supercooled liquid clouds below.
what temp does it need to be for water droplets to freeze in clouds or for spontaneous freezing?
-40 degrees C
deposition nuclei
goes straight to ice crystal, skipping the liquid phase.
freezing nuclei
acts like freezing rain, nuclei have to be immersed in the drop before freezing.
contact nuclei
water that freezes on contact, freezing rain
what is Rime?
When supercooled cloud or fog droplets freeze on contact, they form an accumulation of white granular ice called rime.
what does rain start as in the middle and northern lattitudes?
snow, even in the summer.
what is the most common seen snowflake
dendrite
what cloud do snow grains typically come from?
stratus
what cloud do snow pellets typically come from?
cumulus congestus
what size are snow pellets
2-5 mm
what size are snow grains
less than 1 mm
how much dry snow is in one inch of water?
20 inches
how much wet snow is in 1 in of water.
6 inches
what is virga
rain or drizzle that evaporates before reaching the ground
rain water drop size
greater than 0.5 mm
drizzle water drop size
less than 0.5 mm
down burst
a rain shower that is excessively heavy
rain shower
a brief sporadic rain event
what is classified as heavy snow
4 inches in 12 hours, 6 inches in 24 hours
how are flurries classified
light showers of light dusting snow.
snow squall
a rain shower but with snow.
what vis is considered light snow
greater than 1 ½ mile of visibility
what vis is considered moderate snow
greater than ¼ mile but less than or equal to ½ mile
what vis is considered heavy snow
less than or equal to ¼ mile
what part of the cloud do snowflakes tend to form
relatively warmer portions, -15 degrees C
what effects the size of rain droplets
thickness of clouds and strength of updraft.
what is terminal velocity?
the speed at which raindrops fall
what is the TV of tiny cloud droplets?
0.1 m/s
what is the TV for larger droplets?
6.5 m/s
are cloud droplets bigger than water droplets
no, cloud droplets are much smaller
what do clouds need in order to form cloud droplets
CCNs (dust, salt, aerosols)
which radar product shows the intensity of a thunderstorm
base reflectivity
which radar product shows the direction a thunderstorm is moving
base/radial velocity
what are the two modes of base reflectivity imagery
clear and precipitation
what is the most common tilt of base reflectivity
0.5 degrees
what dBZ level should be concerned about the presence of hail
60 dBZ
which type of precipitation is more centralized and is more intense?
convective
which type of precipitation is more spread out and less intense?
Stratiform
TVS
Tornado Vortex Signature
ice particle collide and stick together, makes snowflakes
aggregation
Accretion
supercooled water freezes on contact with ice falling, hail
Collision
ice crystals or water drops colliding with each other making a bunch of smaller crystals or rain drops.
coalescence
two liquid particles colliding making larger droplets
what causes hail to grow larger
stronger updraft
Note 
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