Cold Fronts Flashcards
What is a cold front?
An area of colder air pushing in to warmer air and forcing that warmer air up over the colder air
https://www.youtube.com/watch?v=OFeN5nMqT7M
What kind of indications are associated with an approaching cold front?
- The temp will still be warmer, since you are still in the warm air relative to the approaching cold air
- The pressure will be steadily falling (at the warm air is forced to rise)
- Visibility will be fair to poor as the air around you is still somewhat stable
- Cumulus clouds -> TC -> CB clouds will form in that order as the warmer air is forced to rise and cool
- You’ll get a short period of showers
The dewpoint will stay high and steady and the winds will be from the south-southwest
What indications are associated with a cold front being right on top of you?
- Sudden drop in temp
- Sudden rise in pressure
- Visibility will be improving as winds pick up and air starts mixing
- CB clouds will be present
- You’ll have heavy rain, TS, maybe hail but it wont last long
Winds are gusty, veering and increasing. Dew point has a sharp drop
What indications are present after the passage of a cold front?
- Temperatures continue to drop
- Pressure continues to rise
- Visibility is good
- The types of clouds now depend on the state of the warm air aloft. Probably patchy cumulus
- Some showers now but clearing quickly
Winds are now coming from west-northwest and dew point is lowering
Why is weather intense but short-lived long the leading edge of a cold front?
Because the warm air is forced to rise so quickly, that creates very unstable air with TS and steady precip. However this weather follows the front as it advances, and since cold fronts advance quickly, from the ground, the weather will also pass by quickly.
https://www.youtube.com/watch?v=YJCW4zuoMM0
What is the order of cloud you will see if you are *standing in the warmer air** ahead of an advancing cold front?
Cumulus, then TCU, then CBs
Basically you’re just going to see a wall of crap advancing toward you. Sometimes, like in this picture, the top of the anvil can be blown out far ahead of the cold front as high cirrus clouds, but not always
What is the weather doing, generally speaking, around a cold front?
At the leading edge of the front there is a narrow band of steady rain, thundershowers, or hail. It is usually pretty dramatic but also short-lived.
Behind the cold front there will usually be patchy cumulous clouds and showery precipitation that quickly drops off
How fast can a cold front move?
Up to 30KTS or more
Typically, how deep is the leading edge of a cold air mass (where most of the weather will happen)?
About 50NM
As the cold front passes by, what kind of cloud formations will you see?
Think of it as the CB and TC clouds that formed at the leading edge of the cold front getting dragged back along the curve of the front.
Typically you would see the clouds move higher. Cumulus form will rise to Nimbostratus, then to Altostratus, then to Cirrostratus (not always exactly this but cloud will generally go from low as the front passes over top to higher and higher the farther away it moves)
**Note in the picture that if the warm air is moist but stable, you would be unlikely to see CBs.
If the warm air mass being shoved up by the cold front is moist but also stable what kinds of cloud is our precipitation going to come from?
Since the warm air is stable, there wont be as much rising, so CBs would be unlikely. More likely the precip will be coming from Nimbostratus cloud
Where is the wind coming from as a cold front approaches vs when it was passed?
Wind will be coming from the south-southwest, will veer (change direction clockwise), and then come from the west-northwest
The source region for any air mass will always be a ____ pressure region
High pressure. Doesn’t matter the temperature of the mass, can be warm or cold, but it will always be high pressure.
Some air masses don’t have the strength to push up a warm air mass (maybe their temp/densities are too close together? I couldn’t find the answer to why). This will lead of a stationary (different from occluded) front. Often accompanied by long periods (days) of rainy, cloudy weather.
Though air masses are regions of high pressure, they will always move/pivot around ____ _________
Low pressure regions
When you are looking at a weather map, where will the weather be happening in relation to the cold front drawn on the map?
The weather will be happening behind the spiky blue line
