Transcript Slide 1

Warm Up
Chapter 20
1. What is an air mass?
2. Give the characteristics of each air
mass below
a. cA
b. mP
c. cT
d. cP
e. mT
20.2: Fronts and Lows
Section 20.2 - Agenda
• What is a Front?
• Types of Fronts
- Warm
- Cold
- Stationary
- Occluded
• Life cycle of a Mid-Latitude Low
What is a Front?
• The boundary that separates
different air masses.
• Usually bring:
1.Changes in Temperature
2.Changes in Wind Direction
3.Changes in Humidity
4.Precipitation
Warm
Cold
Air
1. Cold Front
•Advancing Cold Air
•Forces Warm air up at a Steep slope
•Usually a narrow band of
precipitation
•Cumulonimbus Clouds
2. Warm Front
•Advancing Warm Air
•Warm air rides over cold air at a
low slope
•Usually a wide band of
precipitation
•Brings thinner, layered clouds
Warm Air
Cold Air
Vis 2002
3. Occluded Front
•Cold Front catches up to
Warm Front since cold fronts
move twice as fast.
•Warm air is squeezed up,
forming clouds.
4. Stationary Front
•Front is Not Moving.
•Warm air still rises above cold
air, bringing clouds and
precipitation.
•Can lead to flooding.
END
Life Cycle of a MidLatitude Low
•Fronts are usually connected
to Low Pressure systems.
•As the Low spins, the fronts
move and Cold front catches
up to Warm.
•Takes 12 to 24 hours to get
to stage 3.
Upper Air Flow
•Upper
Air Flow
steers
the
Low
along
Weather associated with Pressure Systems
As a Low moves near, the weather will
change.
A
C
B