Where is radiation fog most likely to form on a cold winter morning?
by the surface in the valley because cold air is denser and sinks
How does radiation fog 'burn off'?
The long wave radiation warms up the atmosphere, causing the temp to rise, and the air rises and mixes, then the temp goes higher than the dew point, since the temp and dew point are no longer married, it creates fog, mixes out from THE BOTTOM UP
What process is mainly involved BEFORE condensation occurs?
Long wave radiation goes skyward, so the cooling occurs due to radiation, then the dew point can match the temp and condensation can occur
How are clouds named?
according to shape/appearance and by the height of the cloud base above the surface
What are the 4 types of clouds?
Low, Mid, High, Vertical Dev
Vertical Development
Cumulus, Cumuluscongestus, Cumulonimbus (thunderstorms)
Low Clouds
Nimbostatus (precipitation), Stratus, Stratocumulus
Middle Clouds
Altocumulus (grey & puffy), Altostratus (blueish-grey, cannot discern on cloud from another)
High Clouds
Cirrus, Cirrocumulus, Cirrostratus
Lentricular Clouds
caused as moist air crosses a mountain barrier, layered like pancakes
Satellite imagery obtained when the Earth is dark can only be...
Infrared imagery
During daylight, we can obtain both...
infrared and visable satellite imagery
Why are infrared satellite images computer enhanced?
to see differences in temp and altitude of clouds
What are the particles in the atmosphere on which water vapor condenses for cloud formation?
condensation nuclei
How does frost form?
on a clear, cold night w/ a low dew point, water as vapor going to water as solid and skipping the solid phase = deposition
Air is said to be stable when...
vertical motions are resisted, the blob wants to sink back down
Air is said to be unstable when...
vertical motions are enhanced, blob rises, expands, and cools
Which set of conditions, working together, would make the air most stable?
low environmental lapse rate (3 or 4 degrees C)
Most unstable?
steep environmental lapse rate, rate must be greater than 10 degrees C
Why are the moist and dry adiabatic lapse rates different?
because moisture varies, whereas dry is constant, moist is ALWAYS under 10C b/c of condensation/saturation makes the clouds from, causing latent heat to be released
Dry Adiabatic LR?
10 degrees C per 1000 km, CONSTANT
Moist Adiabatic LR?
3-9 degrees C per 1000 km, VARIES
Environmental LR?
found by sending up a radiosonde
What is meant by 'conditional instability'?
starts as dry, stable air, becomes unstable as particle goes up and becomes saturated; occus when the ELR is between the MALP and the DALP
What is the best set of conditions to produce the kind of convective instability associated with severe thunderstorms and tornadoes?
surface = warm, moist air
aloft = dry, cold air
How does the temp of a parcel of sinking air change?
temp increases due to compression, just like the molecules pressed together in a bike pump
What kind of separation between the temp and the dew point (starting on the surface) would be the best for the formation of a cumulus cloud with a high base above the ground?
the air must be dry, big seperation between dew point and temp
What kind of separation between the temp and the dew point (starting on the surface) would be the best for the formation of a cumulus cloud with a low base above the ground?
temp and dew point at the surface to be close together
How does subsidence affect stability?
subsidence - air parcel is sinking
air will be stable if sinking
In the collison-coalesce process of precipitation formation (in warm clouds/tropics) there are no_______ in the cloud.
Ice crystals
What is the main difference between a cloud droplet and a rain droplet?
Size! It takes 1 mill. CD to make 1 RD.
What does the terminal velocity (how fast it falls of a large raindrop compare to that of a small raindrop?
It is faster.
In a sub-freezing cloud, how does the saturation vapor pressure of a liquid water drop compare to that of an ice crystal?
Ice crystals are attracting the super-cool water droplets, therefore the ice crystals has a lower saturation vapor pressure to attract water droplets, which have a a higher saturation vapor pressure
Why is snow more common in the winter than in summer?
The temp at the surface has to be at or below freezing; water droplet starts out as snow, and if the temp is correct, will remain as snow as it falls, then the ground must be cold freezing for it to remain as snow once fallen
Hail
particles get caught in updraft winds and collect more ice/water molecules when they reach the above the freezing level in the cloud, then gets caught in a downdraft, then possibly up and down again.
Snow
precipitation starts as snow and remains frozen while falling and hitting the ground
Sleet
precipitation starts out as snow, melts, encounters cold air and hits the ground as little pellets
Freezing rain
Snow melts and becomes rain, encounters VERY cold air as it falls and freezes, on contact, producing ice on everything
How does snowfall protect plants?
it insulates the roots
How does radar work?
it sends an emitter (radio pulse) to hit objects in clouds and reflects back, then algorithms determine the distance of the clouds from the radar, intensity, etc.
How does cloud seeding work?
silver iodine is artificially added to ice nuclei in clouds to coax/pull out more supercold nuclei out of the cloud to make more snow, possibly 5-20% more snow
Explain why the surface air on the downwind side of a mountain barrier can be drier than the surface air on the upward side. What is this effect called? Where does this actually happen in the US?
On the windward side of mountains, the air parcels rise expand and cool leading to condensation, cloud formation and precipitation. On the Leeward side of the mountain, air parcels sink, compress and heating, leading them to dry out. This creates what is