Download Types of Fronts Stationary front

Types of Fronts
Stationary front
A front that is not moving.
Types of Fronts
Cold front
is a leading edge of colder air that is
replacing warmer air.
Types of Fronts
Warm front
is a leading edge of warmer air that is replacing
cooler air.
Types of Fronts
Occluded front:
When a cold front catches up to a warm front.
Types of Fronts
Dry Line
Separates a moist air mass from a dry air mass.
A. Cold Front
is a transition zone from warm air to cold air.
A cold front is defined as the transition zone
where a cold air mass is replacing a warmer air
mass.
Cold fronts generally move from northwest to
southeast.
The air behind a cold front is noticeably colder
and drier than the air ahead of it.
When a cold front passes through,
temperatures can drop more than 15 degrees
within the first hour.
The station east of the front reported a temperature of 55
degrees Fahrenheit while a short distance behind the front, the
temperature decreased to 38 degrees.
An abrupt temperature change over a short distance is a good
indicator that a front is located somewhere in between.
B. Warm Front.
• A transition zone from cold air to warm air.
• A warm front is defined as the transition
zone where a warm air mass is
replacing a cold air mass.
Warm fronts generally move from southwest
to northeast .
The air behind a warm front is warmer and more
moist than the air ahead of it.
When a warm front passes through, the air
becomes noticeably warmer and more humid
than it was before.
Diagram of Warm and Cold Fronts
Looking at a Cold Front in more detail
Another view of a Cold Front
Looking at details of a Warm Front
Another view of the Warm Front
C. Stationary Front a front that is not
moving.
When a warm or cold front stops moving, it
becomes a stationary front.
Once this boundary resumes its forward motion, it
once again becomes a warm front or cold
front.
A stationary front is represented by
alternating blue and red lines with blue
triangles pointing towards the warmer
air and red semicircles pointing towards
the colder air.
D. Occluded Front - when a cold front overtakes a warm
front.
A developing cyclone typically has a preceding warm front (the
leading edge of a warm moist air mass) and a faster moving cold
front (the leading edge of a colder drier air mass wrapping around the
storm).
North of the warm front is a mass of cooler air that was in place
before the storm even entered the region.
As the storm intensifies, the cold front rotates around the storm
and catches the warm front.
This forms an occluded front, which is the boundary that separates
the new cold air mass (to the west) from the older cool air mass
already in place north of the warm front.
Symbolically, an occluded front is represented by
a solid line with alternating triangles and
circles pointing the direction the front is
moving.
Formation of an Occluded Front
Special situation of an Occluded Front
Isobars: connect areas with equal air pressure
The distance between the isobars is called the
pressure gradient
• The closer the
isobar lines, the
greater the
change in air
pressure, and the
greater/faster
the winds speeds.
On the previous weather map ;
Dew points east (ahead) of the dry line shown above range from
the upper 50's to low 70's with winds from the southeast.
West of the dry line, dew points were in the 20's and 30's, a
decrease of nearly 50 degrees.
Air temperatures ahead of the dry line were generally in the 70's
and 80's while behind the dry line, temperatures ranged from the
mid 80's to mid 90's.
Drier air behind dry lines lifts the moist air ahead of it, triggering
the development of thunderstorms along and ahead of the dry line
(similar to cold fronts).
It is not uncommon for tornadic super cells to develop along a dry
line.