Transcript Chapter 12 Meteorology

Chapter 12 Meteorology
Section 12.1 The causes of weather
Meteorology is the study of
atmospheric phenomena.
Meteor is Greek for “high in air”
Clouds, rain drops, snow flakes,
fog, dust and rainbows are known
as “meteors”
Weather is the current state of the
atmosphere (short term)
Climate is the long term conditions
of the atmosphere in a given region.
Average over the
course of 30 years.
Chapter 12 Meteorology
How is the radiation
coming to Earth
distributed?
The continual motion of
the air and water distribute
the heat energy around the
Earth. (nature abhors a
vacuum)
This difference in
temperature creates a
pressure difference and
therefore a wind (flows
from high to low pressure)
Chapter 12 Meteorology
The Suns rays strike
the Earth’s surface at
different angles
depending on the
location and time of
year. During the
spring and fall
equinox (Latin for
equal night) the
equator receives the
Suns direct rays.
Chapter 12 Meteorology
During the northern hemispheres summer the Sun’s rays
are hitting the Earth at 90 degrees at 23.5 degrees North
latitude. This is the Tropic of Cancer.
In the winter, it is the opposite. The Suns rays will strike
the Earth’s surface at 23.5 degrees south latitude.
Chapter 12 Meteorology
Air mass: A large body of air that takes on the
characteristics of it’s source region (area where it develops)
Chapter 12 Meteorology
The air mass picks up two
characteristics from it’s source region.
1. Humidity
2. Temperature
Combinations are in your ESRTs!
Polar and arctic means cold.
Tropical means warm
Continental = Dry
Maritime = Moist
Air mass modification: The air mass
begins to take on the characteristics
of the region it is traveling over.
Front: Boundary between two air
masses
Section 12.2 Weather Systems
Coriolis effect: The wind deflects to the right in the
northern hemisphere because the Earth is rotating west to
east
Section 12.2 Weather Systems
Trade Winds: Occur at 30 degrees north and south latitude.
Horse latitudes: Region of high pressure and little if any
winds. This is an area of wind divergence.
*On a side note, sailors who were caught here often tied the
horses to their boat to pull them in a desperate effort to
escape this windless region. Later, if they were starving,
they would resort to eating their cargo (i.e. the horses) Pass
the A-1!
More sailors lost in the horse latitudes
ITCZ (Inter tropical convergence zone): Near the equator
the trade winds from both hemispheres come together in an
area of convergence. The location of the ITCZ changes
with the seasons due to the difference in the angle of
insolation (sun light).
Here you see the ITCZ shift between January and July
These two wind belts flow all the way around the Earth.
The Prevailing Westerlies : Wind belts that flow between 30
and 60 degrees North and South latitude
The Prevailing Easterlies : Wind belts that flow between 60
degrees and the poles North and south latitude(90 degrees).
Jet stream: The narrow band of fast moving (185 km/hr)
wind that is high in altitude (10.7-12.2 km) within the
westerlies.
This diagram is
in your ESRTs
so you do not
have to copy it
in your
notes!
These two wind belts flow all the way around the Earth.
The Prevailing Westerlies : Wind belts that flow between 30
and 60 degrees North and South latitude
The Prevailing Easterlies : Wind belts that flow between 60
degrees and the poles North and south latitude(90 degrees).
Jet stream: The narrow band of fast moving (185 km/hr)
wind that is high in altitude (10.7-12.2 km) within the
westerlies.
So what’s with this picture?
You might not believe it the answer!
Just read, do not write down...
Fugos: Japanese Balloon Bombs of WWII
Officially; in the waning days of the Pacific War Japan
tried a last ditch ploy to hit the United States with a
terror weapon. That weapon was the Balloon Bomb. It
was supposed to set fire to the West Coast and drop antipersonnel bombs randomly on the U.S. In research after
the war it was found that the Japanese built 15,000 of
them but only launched 9,300. A little over 300 Balloon
Bomb incidents occurred in the U.S. and Canada. The
only casualties were a woman and five kids in By,
Oregon on a church picnic, who found and moved one. It
exploded, killing them all. Luckily they did not have the
technology for the A bomb.
Front: Boundary between two air masses.
There are four types of fronts.
Cold fronts : When a cold air mass pushes into a region
of warmer air. They act like a bulldozer and shoves the
warm air up and out of the way. The steep slope of the
cold front makes the air rise quickly and can generate
narrow intense but short lived storms. Cold fronts move
twice as fast as warm fronts.
After a cold front passes by, cold temperatures are to be
expected.
Warm front: Advancing warm air displaces cold air
creating a gradual slope (unlike the steep slope counter part
the cold front). This means air rises slowly and the rain is
not as intense but will last a longer period of time over a
broader area.
After a warm front passes, the area will experience
warmer temperatures
Stationary Front: Neither the cold front or warm front
advances. Rarely intense storms, acts more like a warm
front in terms of precipitation patterns.
Occluded Front: The front produced when the cold front
catches up with the warm front. The precipitation that this
causes is often referred to as a “mixed bag”. Warm
precipitation then passes through a layer of cold air.
Low Pressure systems: Air flows counter clock wise and
into a low pressure center, upon converging it rises. What
happens to air as it rises???
1. The temperature decreases
2. The dew point temperature
is reached.
3. Water vapor condenses
on condensation nuclei
4. Clouds form.
If there is enough energy and rapid rising of air storms form
5. If there is enough energy
and rapidly rising air, storms
form
High pressure systems: The direct opposite of low
pressure systems. Air flows out, clock wise as air is
sinking. If air is sinking, it is stable and increases in
air temperature and there fore is getting farther away
from the dew point temperature. This results in few if
any clouds and cooler temperatures.
12.3 Gathering Weather data
Thermometer: Measures temperature
Barometer: Measures air pressure (AKA
barometric pressure)
Anemometer: Measures wind speed
Hygrometer: Measures relative
humidity.
Sling psychrometer: (picture on right) Is
a type of hygrometer that uses the wet
bulb and dry bulb thermometers
12.3 Gathering Weather data
Rain gauge: Collects and measures rain fall amounts
Ceilometer: measures the heights of clouds (you will do
this with a LCL chart instead)
Radiosonde: A weather balloon that
carries sensors to determine the air
temperature, pressure and humidity
at about 30,000 m up
Doppler Radar: The change in wave frequency as energy
(sound or light) moves towards or away from and observer.
Infrared Imagery: Satellites can be equipped to take images
based on differences in thermal temperature. The higher the
cloud lighter the color. Because storm intensity is related to
how high a thunderstorm cloud reaches, this is useful when
trying to determine how severe a storm will be.
Station Model: A record of weather for a particular site at a
given time. This gives you a lot of information and can be
found in your ESRT’s. As you are learning, making a
station model for your weather journal will get easier and
easier. This one has more detail than you need to learn...
Iso pleth or Iso line: A line that connects areas of equal
value. examples
isobars: lines that connect areas of equal pressure.
isotherms: lines that connect areas of equal temperature.
Accuracy of Forecast declines with time
Who has a better chance at predicting a long term forecast?
a) The Weather person on TV
b) Old people with arthritis
c) Your Earth Science teacher
d) Miss Cleo
The answer is...
But if you said Mr.. McGuire you get an “A”
and it won’t cost you $3.95 per minute!!!
1. Which of the following is not a front?
A. Occluded
B. Coriolis
C. Stationary
D. Cold
2. How does air move in a low pressure system?
A. Clockwise, in and down
B. Counter clockwise, in and up
C. Counter clockwise, down and out
D. Clockwise, down and out
3. Where was a continental polar air mass that is
affecting the united states most likely developed?
A. Mexico
B. Gulf of Mexico
C. North Pacific
D. Northern Canada
4. What are the two characteristics of an air mass?
A. Temperature and Humidity
B. Temperature and Pressure
C. Humidity and Pressure
D. Pressure and Density
***Bonus. Draw the Earth in the four positions
around the Sun showing the start of each season.
Make sure you clearly show the tilt direction and label
the correct dates for the beginning of each season.
Also make sure to show there is a difference between
the distance to the Sun in the summer position
compared to the winter position. This can be
exaggerated as I am not expecting this to be to scale.