FRONTS Flashcards
Define Front
A transition zone between two air masses as it appears on the surface
Frontal surface
The sloping side of the cold air
What is the movement of the front dependent on?
The motion of the cold air that is perpendicular to it
The name of the front is always determined by:
The motion of its cold air
Types of fronts:
Cold front
Warm front
Occluded front
Trowal
Stationary front
Upper front
When does The transition zone (leading edge of a cold air mass) form?
When a wedge of cold air forces its way under a warm air mass called a frontal lift.
How fast can a cold front move
At speeds of 30 KT or more
Before a cold front passage
B.C
S,W,F,C,S,F,H
Some water flows cold some flows hot
Winds – beginning in the south to Southwest
Temperature – warm
Pressure – falling steadily
Clouds – increasing cumulus, towering cumulus, and cumulonimbus
Precipitation – short periods of showers
Visibility – fair to poor- haze
Dewpoint – high – remains steady
As cold front passes
D.C
G,D,R,CB,TS,P,D
Winds – gusting and veer and increase
Temperature – sudden drop
Pressure – sharp rise
Clouds – CB
Precipitation – formed by warm air, expanding as it is lifted by the advancing, cold air. Heavy rain, thunder and lightning, and maybe hail
Visibility – poor but improving
Dewpoint – sharp drop
After cold front passage
A.C
WDRWGL
Winds – becoming a West in Northwest
Temperature – steadily dropping
Pressure – rising steadily
Clouds, - slow, moving, warm air, stable, NS, AS, CI, fast, moving, warm, air, unstable, CU
Precipitation – showers, then clearing
Invisibility – good, except for in the showers
Dewpoint – lowering
Define warm fronts
A mass of warm air advances on a retreating mass of cold air. The warm air being lighter, ascends over the cold air in a long, gentle slope.
Before warm front passage
B.W
Winds – beginning in the south to Southwest
Temperature – cool to cold with slow warming
Pressure – falling gradually
Clouds – approaching in order: Sirus, cirrostratus, alto, stratus, Nimbo, stratus, stratus, and sometimes fog. CB in summer when fast moving and warm air is unstable TCU also likely when air is unstable.
Precipitation dash light to moderate: rain, snow, sleet, or drizzle
Visibility – poor
Dewpoint Dash steady rise
As a warm front passes
D.W
Winds– variable and veers
Temperature – steady rise
Pressure - levelling off
Clouds – stratus type, NS when there is precipitation
Precipitation – drizzle or none
Visibility – poor but improving
Dewpoint Dash steady
After warm front passage
A.W
Winds– becoming a south to south west
Temperature – warmer than steady
Pressure – slight rise, followed by fall
Clouds – clearing with scattered Strato cumulus SC, occasionally CB in summer
Precipitation – commonly none, sometimes light, rain, or showers
Visibility – fair in haze
Dewpoint – rise, then steady
Occluded front
This happens when a cold front associated with a low catches up to the warm front - over, taking it and undercutting the warm front
