Air Masses, Fronts, and Pressure Systems
6.4.4: Summarize the relationship of the movement of air masses, high and low pressure systems, and frontal boundaries to
storms (including thunderstorms, hurricanes, and tornadoes) and other weather conditions.

Essential question: How do air masses, pressure systems, and fronts influence weather conditions?
Air Masses

Huge bodies of air that form over ____________or ____________ in ___________ and polar regions.

______________________and ___________________conditions (for example, warm or cold air, humid or dry air)
within the air masses as they form are important to the resulting weather conditions when air masses move.

Warm, moist air masses are often associated with __________________ conditions like thunderstorms, tornadoes,
and hurricanes.

__________________, moist air masses are often associated with large snowfall, blizzards, freezing rain, and sleet.

Warm, _____________ air masses are often associated with sunny, warm weather conditions.

Cold, dry air masses are the opposite. They are associated with _____________, __________________ weather
conditions.
Fronts

As theses air masses move and collide with each other, ______________ form at the boundaries between the air
masses.

Depending upon the ___________
_______________ involved, a warm front, cold front, stationary front, or
occluded front can develop.
WARM FRONT

When a ________________air mass collides and rides over a ________________air mass, the resulting warm front
may produce ________________periods of precipitation and warmer temperatures. High level ______________
signal the approach of a warm front.
COLD FRONT

When a _________________ air mass collides and slides under a ______________ air mass, the resulting cold front
may produce ___________________________ and sometimes tornadoes and cooler temperatures. Cumulus clouds
build quickly as the front approaches.
STATIONARY FRONTS

When _________________ a cold air mass nor a warm air mass moves at a frontal boundary, the resulting stationary
front may produce ___________________periods of precipitation which at times may be very heavy. Nimbostratus
clouds are associated with this front.
OCCLUDED FRONTS

When a cold air mass pushes into a warm air mass that is behind a cool air mass, the warm air mass is pushed up above
the cooler air masses. The resulting _______________
_____________________ may bring _________ periods
of precipitation. Cumulonimbus clouds are associated with this front.
High/Low Pressure Systems

Warm air rising or cold air sinking combined with the _____________ of the Earth causes the air to spin forming
________ and ____________ pressure regions.

High pressure systems signal more _________
_______________with winds circulating around the system in a
clockwise direction.

Low pressure systems with counterclockwise winds often result in _____________ and/or stormy conditions.
Storms

Severe weather conditions called _____________ occur when pressure _________________ cause a rapid air
movement.

Conditions that bring one of kind storms can also cause other kinds of storms in the same area.
THUNDERSTORM

A thunderstorm is a storm with thunder, lightning, heavy rains and strong winds;

Form within large ______________________________ clouds;

Usually from along a _________________________ front but can form within an air mass.
TORNADOES

A _______________________ is a rapidly whirling, funnel-shaped cloud that extends down from a storm cloud;

The very ____________ ____________________ and strong winds can cause great damage to people and property;

Are likely to form with the frontal regions where strong ________________________ are also present.
HURRICANES

A hurricane is a low pressure ____________________ storm that forms over ______________ ocean water;

Winds form a spinning circular pattern around the center, or eye, of the storm;

The _________________ the air pressure at the center, the ________________ the winds blow toward the center
of the storm.
Use your notes to complete the questions and chart.
1.
What is an air mass?
2.
What is in the air mass that is important to understanding the resulting weather conditions?
DRAW THE SYMBOL
FOR THE FRONT
ASSOCIATED WITH
CUMULUS CLOUDS
PRODUCES LONG
PERIODS OF
PRECIPITATION
ASSOCIATED WITH
STRATUS CLOUDS
BRINGS STRONG
STORMS
WARM AIR MASS
CAUGHT BETWEEN A
COLD AND COOL AIR
NEITHER AIR MASS
MOVES
COID AIR MASS
OVERTAKES A WARM
AIR MASS
WARM AIR MASS
OVERTAKES A COLD AIR
MASS
Complete the chart by placing an “X” in the appropriate column.
WARM
FRONT
COLD
FRONT
STATIONARY
FRONT
OCCLUDED
FRONT
3. What does a high pressure system usually indicate?
4. What does a low pressure system often bring with it?
5. What type of pressure system is associated with thunderstorms, tornadoes, and hurricanes? Think carefully.
6. Where do hurricanes form?