Download Chapter 16 Weather Factors Notes

1. Heat Energy
2. Air Pressure
3. Winds
4. Moisture
ENERGY IN THE
ATMOSPHERE
• Most energy in the atmosphere
comes from the sun.
• Electromagnetic Waves- sun’s
energy that travels to earth.
• Classified by wavelength
(distance between waves).
ENERGY WE RECEIVE
FROM THE SUN
• Most of the sun’s energy
travels to earth in the form of
1. visible light
2. infrared radiation
3. ultraviolet radiation.
VISIBLE LIGHT
• Includes all colors of rainbow
• Different colors = different
wavelengths
• Red/Orange = longest
wavelengths
• Blue/Violet = shortest
NON-VISIBLE RADIATION
1. INFRARED- long waves, not
visible but can be felt as heat.
2. ULTRAVIOLET (UV)shorter waves, can cause
sunburns.
Energy in the Atmosphere
1. Sun’s energy travels in the
form of waves.
2. Some sunlight is absorbed by
the atmosphere before it
reaches the surface. Ozone
layer & water vapor absorbs
sun’s energy.
3. Most of the sun’s energy is
absorbed by land/water &
changes into heat.
4. The earth’s heated surface
then radiates most of the
energy back into the
atmosphere as infrared
radiation.
4b. Some of the infrared rays
get absorbed by water vapor,
carbon dioxide, & other gases.
• This heats up the air & forms a
heat “blanket” around earth.
•Carbon dioxide & other gases
act like a blanket trapping heat
in the air.
•Infrared rays can’t escape into
the atmosphere thus keeping the
heat on earth.
Scattering- reflecting light in
all directions. Gas particles
scatter short wavelengths
(blue/violet) more.
SCATTERING EFFECTS
Scattered light looks bluer than
ordinary light which is why the
sky looks blue.
• Sunrise/Sunset- light passes
through a greater thickness at this
time so more orange/red light gets
through.
Sec. 2 HEAT TRANSFER
TEMPERATURE
• The average amount of
energy/motion of a particular
substance.
• A measure of HOT/Cold.
• Particles are constantly moving,
the faster the particles are moving–
the more energy they have.
THERMAL ENERGY
• Total energy motion in the
particles of a substance.
• Iced Tea has less thermal
energy than Hot Tea.
Thermometer
•Measures air temp.
•The liquid will expand if its
hot or contract if it is cold.
TEMP. IS MEASURED IN
• CELSIUS SCALE (scientists)
• 0C water freezes, 100C boiling
point of water.
• FAHRENHEIT SCALE (US)
32F water freezes, 212F boils
3 WAYS HEAT IS
TRANSFERRED
1.Conduction
2.Convection
3.Radiation
• Direct transfer of heat energy
from 1 substance to another.
• Hand touching a hot stove
• Earth absorbs sun’s energy &
the surface becomes warm.
• transfer of heat energy in a fluid
(gas/liquid).
• Air near earth’s surface is heated,
it becomes less dense & rises.
Cooler air sinks.
• Most of the heat energy in the
atmosphere is transferred this way.
• Transfer of heat energy
through space in the form of
waves.
• Heat from the sun reaches
earth by radiation
How the Troposphere is
Heated
1. Sunlight enters as radiation.
2. As earth warms, heat is
absorbed by the surface
(conduction).
3. Heat from the surface rises
into the atmosphere
(convection).
Heat is transferred through the
troposphere by convection.
WIND
•Caused by the unequal
heating of the earth by the
sun.
•Horizontal movement of air
from an area of High
Pressure to an area of Low
Pressure.
WIND MOVEMENT
• When air is heated, atoms
expand & is less dense, rises =
Area of Low Pressure
• When air cools, particles slow
down/come together & is more
dense, sinks = Area of High
Pressure.
Cooler (denser) air moves in
underneath warmer (less
dense) air.
MEASURING WIND
Wind vane- measures wind
direction, the name of the
wind tells where the wind
started.
South Wind blows from the
south towards the north.
• Anemometer- uses a set of
cups that spin on an axel.
Wind turns the cups & a
meter measures the speed.
(MPH or Knots.)
WIND-CHILL FACTOR
• A measure of how cold you
feel when outside in cold
temps.
• Wind blowing over skin
removes heat from your body.
(stronger the wind, the colder
you feel)
ANGLE OF SUN’S RAYS
•Most direct sunlight occurs
at equator. The farther away
from equator, the less radiant
energy you receive.
•Equator- hot, Poles- cold
2 TYPES OF WINDS
1.Global Winds- blow from
specific directions, cover
long distances
2.Local Winds- blow from
any direction, cover short
distances
Types of Local Winds
Seabreeze- flow of air from
sea to land. Cool air from sea
takes rising warm air’s place
land.
2. Landbreeze- flow of air
from land to sea. At night, Land
cools off faster than water,
cooler land air replaces warm
rising air from the sea.
•Warm air at equator rises &
moves toward the poles. At
poles, cooler air sinks & moves
toward equator.
GLOBAL WIND BELTS
•Apparent shift in the path of
the wind due to rotation of
the earth.
•e curve to left.
CORIOLIS EFFECT
• All winds in the Northern
Hemisphere curve to the right
as they move towards the
equator. Winds in Southern
Hemisphere curve to left.
1.DOLDRUMS- at equator,
very little wind, air is warmed
rapidly creating an area of
Low Pressure.
2. TRADE WINDS- 30N/S of
equator, warm air starts to cool &
sink creating wind, High Pressure.
3. PREVAILING
WESTERLIES- strong winds
60N & S latitude, plays a role in
weather of United States.
4. POLAR EASTERLIES- cold,
weak winds. Causes many
changes in weather in US.
Bands of High Speed winds
about 10km above Earth’s
surface.
Usually blow west to east at
speeds of 200 to 400kmph.
Pilots can save time/gas
• The movement of water
between the atmosphere &
the earth’s surface.
• Process by which water molecules
escape into the air.
• Moisture enters into the air.
• Sun’s energy turns liquid water
into a gas or water vapor. Winds
carry it all over the earth.
•Water vapor or moisture
in the air
•Varies from place to
place
•Percentage (%) of
moisture the air holds
relative to the amount it
can hold at a given temp.
Example
• At 80F, 1kg of air can hold
12g of moisture.
It’s only holding 9g now so the
relative humidity 9/12 X 100
= 75%
PSYCHROMETER
•Instrument that measures
relative humidity
•2 thermometers used: dry,
wet one
• When air passes over the wet bulb,
water in the cloth evaporates &
cools the wet bulb temp.
Low Humidity = evaporation goes
quickly, temp drops quickly
High Humidity = evaporation goes
slowly, temp hardly changes.
Reading the Chart
• Subtract the two temps
• Take that number & look for it
on the chart & match it with
the dry bulb temp. to get the
humidity.
Holding Moisture
• Warm air holds more moisture
at earth’s surface than cold air.
• As the warm air rises, it can no
longer hold as much moisture
so it condenses & changes to a
liquid (rain).
DEW POINT
• The temp. at which water
vapor condenses.
• Condensation- process where
water vapor becomes liquid
water.
CLOUD FORMATION
• Formed when moisture in air
condenses
• A mixture of liquid (water)
suspended in a gas (air).
DEW
• Formed when the ground
reaches the temp. at which
water vapor condenses.
• Dew Pt. Above freezing =
water vapor forms water
droplets
• Dew Pt. Below freezing = frost
2 FACTORS FOR CONDENSATION
1. The cooling of air to the dew
point or below.
2. The presence of particles
(salt, dust from soil, &
smoke)
1. Cumulus
2. Stratus
3. Cirrus
CIRRUS CLOUDS
•Feathery with tails
•Indicates rain or snow will
fall soon
CUMULUS CLOUDS
Fluffy, white cotton balls
•Indicates fair weather, large &
dark, thunderstorms are likely
(cumulonimbus clouds)
•Nimbus = rain
•Alto = high
STRATUS CLOUDS
• Smooth, gray clouds that
cover the whole sky & block
out the sun.
• Rain or drizzle, FOG
Precipitation
*Any form of water that falls
from the clouds & reaches
earth’s surface.
*Rain, sleet, snow, hail
TYPES OF PRECIPITATION
1. Rain- most common, drops of
water less than .5 mm.
Smaller drops- drizzle then
mist.
2. Sleet- raindrops that freeze
into solid particles of ice.
3. Freezing Rain- rain that
freezes once it hits a cold
surface. Doesn’t freeze in the
air.
4. Snow- water vapor in a cloud
is converted to ice crystals
(snowflakes).
5. Hail- round pellets of ice
larger than 5mm. Ice pellets
are tossed in clouds, gain
layers of ice, & turn into hail.
DROUGHT
•Long periods of unusually
low precipitation
•Drier than usual
RAIN GAUGE
•A container that collects
and measures rainfall.
•Measured in mm, cm,
SNOWFALL MEASURING
• Usually measured with a
measuring stick or by melting
collected snow & measuring
the water depth.
• 10cm of snow = 1 cm of rain