Download Name Date

Name __________________________
Date_________
DBQ- Types of Frontal Zones
Cold front
A cold front is defined as the leading edge of a mass of air which is
usually colder and drier than the air mass in front of it, outside of
terrain effects. The colder air, being denser, wedges under the less
dense warmer air, lifting it, causing the formation of mostly
cumuliform (puffy, cotton-ball-like) clouds. The passage of a cold
front usually results in velocity changes in winds and creates vertical
movement of air (uplift) and can set off atmospheric disturbances
such as rain showers, thunderstorms, tornadoes, and snowstorms
ahead of and immediately behind the moving cold front. The air
behind the cold front is generally drier and cooler than that which it
is replacing. On weather maps, the surface position of the cold front
is marked with the symbol of a blue line of triangles pointing in the direction of travel. Cold fronts can move
up to twice as fast as warm fronts.
Warm front
A warm front is defined as the leading edge of a mass of warm air. Warm
fronts move more slowly than the cold front which usually follows. If the
warm air mass is stable, clouds ahead of the warm front are mostly
stratiform and rainfall gradually increases as the front approaches. At the
front itself, the clouds can reach the surface as fog. Clearing and warming
is usually rapid after frontal passage. If the warm air mass is unstable,
thunderstorms may be embedded among the stratiform clouds ahead of the
front, and after frontal passage, thundershowers may continue. These may
become organized ahead of the following cold front as a squall line. On
weather maps, the surface location of a warm front is marked with a red
line of half circles pointing in the direction of travel.
Occluded front
An occluded front is formed when a cold front overtakes a warm front. The two fronts curve up naturally
into the point of occlusion, also known as a triple point.
There are two types of occlusion, the warm and the cold. In a cold occlusion, the
air mass overtaking the warm front is cooler than the cool air ahead of the warm
front, and plows under both air masses. In a warm occlusion, the air mass
overtaking the warm front is not as cool as the cold air ahead of the warm front,
and rides over the colder air mass while lifting the warm air.
A wide variety of weather can be found along an occluded front, with
thunderstorms possible, but usually their passage is associated with a drying of the
air mass. Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and
triangles pointing in direction of travel. Occluded fronts usually form around mature low pressure areas.
Stationary front
A stationary front is a boundary between two different air
masses, neither of which is strong enough to replace the
other. They tend to remain essentially in the same area for
extended periods of time, usually moving in waves. A wide
variety of weather can be found along a stationary front, but
usually clouds and prolonged precipitation are found there.
Stationary fronts will either dissipate after several days or
devolve into shear lines, but can change into a cold or warm
front if conditions aloft change. Stationary fronts are more
numerous in the summer months. Stationary fronts are
marked on weather maps with alternating red half-circles and
blue spikes pointing in opposite directions, indicating no
significant movement.
!!!!!!!!!!!!!!!!!!!!ANSWER IN COMPLETE SENTENCES!!!!!!!!!!!!!!!!!!!!!!!!!
1. What is an occluded front? _______________________________________________________
________________________________________________________________________________.
2. What moves faster a warm front or a cold front? _____________________________________
________________________________________________________________________________.
3. Draw the symbol for:
Cold Front
Warm Front
Occluded Front
Stationary Front
4. What season do stationary fronts occur in most? _____________________________________
________________________________________________________________________________.
5. Describe the air behind a cold front. _______________________________________________
________________________________________________________________________________.
6. Where do occluded fronts tend to form? ____________________________________________
________________________________________________________________________________.
7. What is uplift? _________________________________________________________________
________________________________________________________________________________.