Transcript FRONTS - Sandpoint Middle

WEATHER FRONTS
AND
AIR MASSES
Take notes as you go.
These notes can be
used to study for
our next quiz.
Ms. Augustyn - Mr. Swerin
Sandpoint Middle School
Lake Pend Oreille School District
Weather Fronts
This first part of the slide show takes you through several
types of weather fronts. Note the different kinds of
clouds that accompany each front.
Please study each type of front and take notes, as well as
draw pictures and label as you view the slides. Use
your notes to study for the test.
Know: Weather map symbols, how air masses move or
combine to form each type of front, what kind of
weather each front brings, and the type of clouds that
will be found as each front moves into an area.
WARM FRONT
Weather map symbol for warm front
• Fast moving warm air over takes cold air.
• The warm air moves over the cold air because it is
less dense.
• Clouds, storms and rain accompany a warm front
• Warm fronts move more slowly than cold fronts
• In winter, warm fronts bring snow.
WARM FRONT Study this diagram, the
picture, and the weather map symbol.
This warm front
will first be seen
in St. Louis.
Weather map symbol for warm front
First clouds that you would see would be
cirrus, then they would develop into
cirrostratus as the front moves in. The
clouds thicken and form altostratus, then
eventually nimbostratus clouds form.
Picture of
cirrus
clouds
Weather map details showing a warm front moving towards St. Lous
WARM FRONT
CLOUDS
Weather map symbol for warm front
CIRRUS clouds form first and are seen before other clouds
when a warm front begins moving in.
Cirrus clouds are followed by CIRROSTRATUS,
ALTOSTRATUS and then NIMBO STRATUS which brings rain
and warm temperatures (except in the winter it will bring snow.)
Remember, the warm air moves up and over the
cooler air because it is less dense then the cool air
WARM FRONT
•The air pressure drops when a warm front moves in.
•If the warm air is humid, showers and light rain will fall
along the front where the warm and cold air meets.
•If the warm air is dry, scattered clouds will form.
•Because warm fronts move more slowly than cold
fronts, the weather may be rainy or foggy for several
days.
Warm Fronts
Please answer these questions in full sentences
1. If a warm front were moving into Sandpoint, what
kind of clouds would you see first?
2. Do warm fronts move faster or slower than cold
fronts?
3. In a warm front, what does the warm air do? a)
replaces the cold air, b) moves over the cold air,
c) sinks below the cold air
4. What happens to the air pressure when a warm
front moves into an area?
Cold Front Facts
• Cold front: Cold air moves into an area
• Cold air is dense and tends to sink, warm air is less
dense and tends to rise but cools as it rises and the
moisture in the warm air will condense into droplets of
liquid and creates clouds
• If there is a lot water vapor in the warm air, heavy rain or
snow may fall
• If the warm air is dry, then there will be cloudy skies with
no precipitation.
• Cold fronts move quickly, so abrupt weather changes
can occur
• After a cold front, clear skies and cooler temperatures
follow.
COLD FRONT
Weather map symbol for cold front
The first clouds
that a cold front
brings are small
clouds that
eventually form the
towering
cumulonimbus
clouds
Cold air
moves into
St. Louis
first
The leading edge of a cold
front moving into an area
This shows what a cold front looks like on a weather map
COLD FRONTS
Weather map symbol for cold front
Fast moving cold air overtakes warm air.
Warm air is pushed up creating
CUMULONIMBUS CLOUDS which bring
heavy rain followed by clear weather.
Remember the
last clouds to
develop are the
large
cumulonimbus
clouds
COLD FRONTS
Often bring VIOLENT THUNDERSTORMS in the
spring and summer. (Tornadoes in the mid-west)
The AIR PRESSURE RISES after a cold front
passes.
Cold Front Questions
Please answer these questions in full sentences
5. What kind of air does a cold front bring?
6. What happens to the air pressure after a cold front
passes?
7. What is the major type of cloud associated with a
cold front?
8. How does the cold air in a cold front affect the warm
air?
9. Do cold fronts move faster or slower than a warm
front?
10. What situation would cause a cold front to have no
precipitation?
STATIONARY FRONT
Occurs when warm and cold air meet
and neither one of them is strong
enough to move the other one out.
Weather map symbol for stationary front
Weather map symbol for stationary front
STATIONARY FRONT
Where the warm and cool air meet, water vapor in the
warm air condenses into rain, snow, fog, or clouds.
If the two fronts stall, NIMBO-STRATUS or CUMULONIMBUS clouds may form and it may rain/snow for
extended periods of time.
OCCLUDED FRONT
OCCLUDED FRONT
A warm air mass is CAUGHT BETWEEN two
cold air masses. The warm air mass is pushed
upward by the more dense cold air. The
temperature near the ground is cooler.
An INVERSION is formed
where the temperature is
warmer higher up and
colder down below.
Temperature inversions usually are
unhealthy, and the air becomes stagnate
from auto exhaust, and pollution.
Inversions can often last up to a month or
more.
OCCLUDED FRONT
NIMBOSTRATUS CLOUDS may form and
bring rain or snow or freezing rain.
Weather Front Questions
Please answer these questions in full sentences
11. What is a front?
12. Name and describe four types of fronts. Draw
the weather symbol for each.
13. What happens when warm air is stuck between
two layers of cold air?
14. Why are temperature inversions dangerous for
people with respiratory illnesses?
15. Which type of front moves the fastest?
16. What kind of front forms when two air masses
meet and neither can move?
Air Masses
This next section reviews air
masses.
Study each slide carefully and
answer the questions at the
end of this section
AIR MASSES
• Air masses are classified based on
TEMPERATURE and HUMIDITY.
• Temperature and humidity are
dependent upon where the air masses
form.
Air Masses in the United
States move from west to
east by the PREVAILING
WESTERLIES.
There are FOUR air
masses that influence
the weather in the
United States
They occur in combinations
of temperature and humidity
• POLAR
Cold with high
pressure
• MARITIME
Humid (develops
over ocean)
• CONTINENTAL
Dry (develops
over land)
• TROPICAL
Warm with low
pressure
ORIGIN OF AIR MASSES
WEATHER IS DETERMINED BY WHERE AIR MASSES FORM
AIR MASSES
Notice that abbreviation for each type of air mass
MARITIME TROPICAL
• Forms over the Tropics in the Pacific, Atlantic and
the Gulf of Mexico.
• Associated with warm, humid air.
• Atlantic Ocean and the Gulf of Mexico influence the
central and eastern parts of the US.
• Pacific Ocean influences the weather on the west
coast.
• Summer = Hot humid weather that brings
thunderstorms and showers, as well as tornadoes.
• Winter = Heavy rain or snow. (PINEAPPLE EXPRESS)
MARITIME POLAR
• Forms over the cold north Pacific and Atlantic
oceans.
• Usually cool and moist air.
• Affects west coast more than east coast.
• Cool rainy weather in the summer and snow in
the winter.
• Sometimes called Maritime Arctic or Arctic
Maritime.
CONTINENTAL TROPICAL
• Forms over dry areas in the southwest of the US
and Northern Mexico.
• Hot, dry air masses.
• Affects a very small area.
• Hot, dry weather to southern plains.
CONTINENTAL POLAR
• Forms over central and northern Canada and
Alaska.
• Sometimes called Continental Arctic air mass
• Cold dry air.
• Bitter cold air to the central US during the winter
(Artic Express)
• Tornado Alley in the central US in the summer
when the air mass meats the maritime tropical
air mass from the gulf of Mexico.
18.
17.
Each arrow points to different air
masses. For questions 17-22, write
the name of the air mass and
describe what kind of air is flowing
in that direction.
19.
20.
21.
22.
Air Mass Questions
Use full sentences as you answer
23. What two main characteristics are used to
classify air masses?
24. Why do maritime polar air masses have more
effect on the west coast than the east coast?
25. Classify the four major types of air masses
according to whether they are dry or humid.
26. What kind of air mass produces a “pineapple
express” ??
Cyclones and Anticyclones
This next section is about cyclones and
anticyclones.
Make sure you understand the difference
between the two and can draw and
diagram each.
At the end of this section, please answer the
questions in full sentences.
Cyclones and Anticyclones
A cyclone is a storm or system of winds that rotates around a
center of low atmospheric pressure. An anticyclone is a system of
winds that rotates around a center of high atmospheric pressure.
Cyclones (commonly
known as lows)
generally are
indicators of rain,
clouds, and other
forms of bad weather.
Anticyclones
(commonly known as
highs) are predictors
of fair weather.
CYCLONES
SWIRLING CENTER OF LOW PRESSURE
CYCLONES
• LOW pressure area.
• Represented with an L on a weather map.
• Winds SPIRAL INWARD fed by cooler
high pressure air blowing toward the lower
pressure areas.
• Spin COUTER-CLOCKWISE in the
NORTHERN HEMISPHERE.
• Associated with cloudy, storm weather.
• Tornadoes, Monsoons and Hurricanes.
ANTICYCLONE
An anticyclone is a system of winds that rotates
around a center of high atmospheric pressure.
ANTICYCLONE
• HIGH pressure areas
• Represented with an H on a weather map.
• Winds SPIRAL OUT from the center of
high pressure moving towards lower
pressure.
• Spin clockwise in the northern
hemisphere.
• Sinking, dry air causes clear weather.
• Hot in the summer and cold in the winter.
Cyclones and Anticyclones Questions
Answer the following questions using full sentences
27. What is a cyclone?
28. What type of weather does a cyclone
bring?
29. Winds that spiral inward towards a center
of low pressure form what?
Word Review
Make sure you understand the three types
of heat transfer, isobars, isotherms, and
the difference between evaporation and
vaporization.
Conduction
Transfer of heat through actual touching
Example: A metal pan on the stove. The
handle gets hot because the heat from the
flame touches the bottom of the pan, and
then each molecule transfer heat to its
neighbor until the entire pan is hot.
Convection
Transfer of heat through movement.
Example: The air in this room is heated by
the radiator. The air moves about the
room. Remember, the air above the
radiator is heated, expands, becomes less
dense and rises. It is pushed across the
room by hot air rising behind it.
Radiation
The transfer of heat through space
Example: A rock becomes warmed by the
suns rays.
Electromagnetic Spectrum
The spectrum of all light, which includes
radio waves, tv waves, infrared, visible
light, ultraviolet, x-ray, and gamma.
Isobars
Lines on a map joining places that have the
same air pressure
Isotherms
Lines on a map joining places that have the
same temperature
Evaporation
Process by which molecules at the surface
of a liquid, such as water, absorb enough
energy to change to a gaseous state, such
as water vapor.
Example: The water in an aquarium sitting
on the counter will need to replaced due to
evaporation.
Vaporization
The boiling of water causes the molecules
within the water to absorb enough energy
to escape.
Vaporization is associated with boiling and
the molecules escape throughout the
liquid, whereas with “evaporation” the
molecules are escaping from just the
surface.