Transcript UNIT 4 – WEATHER DYNAMICS

UNIT 4 –
WEATHER DYNAMICS
BOOK SECTIONS
• Chapter 13
– Getting started, 13.1, 13.2, 13.3, 13.4, 13.6, 13.8,
13.9, 13.1, 13.13,
• Chapter 14
– Getting started, 14.2, 14.3,14.5, 14.6
• Rest of Chapter 14, 15, 16
– Class Oral Presentations
INTRODUCTION
• WHY IS A STUDY OF WEATHER IMPORTANT TO
OUR LIVES?
– PLANNING AHEAD
• (ex: travel, recreational activity, work)
– SAFETY AND ENGINEERING
• (ex: creating weather-resistant structures)
– ECONOMY
• (ex: careers in meteorology and science)
– SCIENCE
• Researching weather patterns and interactions
WHAT FACTORS AFFECT OUR WEATHER
PATTERNS?
• GLOBAL
–
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–
–
–
–
–
Global Warming
Ocean Currents
Air Masses
Seasons/Angle of
Sunlight
Earth’s rotation
Latitude
Longitude
Air Pressure
• LOCAL
–
–
–
–
–
Elevation/Topography
Proximity to Water
Distance Inland
Vegetation
Cloud Cover
SOME GENERAL TERMS
• WEATHER DYNAMICS is the study of how
water and air cause weather patterns.
• WEATHER
– The short-range forecast; daily conditions.
– Ex:
temperature, precipitation, wind,
humidity, UV
• CLIMATE
– Long-term seasonal trends averaged from annual
data
– Ex:
In the Atlantic Canada Climate
region, winters are cold and
summers are Warm
GLOBAL WEATHER PATTERNS
• 3 MAIN PARTS OF THE EARTH influence
GLOBAL WEATHER:
– ATMOSPHERE  AIR
– HYDROSPHERE  WATER
– LITHOSPHERE/GEOSPHERE  LAND
SOME GLOBAL WEATHER TERMINOLOGY
• GEOGRAPHY
– The study of oceans, continents, countries, ocean
currents, and air currents.
• LONGITUDE
– Vertical lines on maps/globes that show our
position EAST or WEST of the PRIME MERIDIAN
line.
• LATITUDE
– Horizontal lines on maps/globes that show our
position NORTH or SOUTH of the EQUATOR
PRIME MERIDIAN,
GREENWICH, ENGLAND
Some Special Latitude Lines
• ARCTIC CIRCLE:
– 66.5oN, most Northern latitude to receive sun’s rays
on December 21st
• ANTARCTIC CIRCLE:
– 66.5oS, most Southern latitude to receive sun’s rays
on December 21st
• TROPIC OF CANCER:
– 23.5oN, most Northern latitude to receive sun’s
vertical rays on June 21st
• TROPIC OF CAPRICORN:
– 23.5oS, most Northern latitude to receive sun’s
vertical rays on June 21st
Some Special Latitude Lines. . .
Be able to identify these on a test!
Latitude Lines and Seasons
On December 21st, NOTICE how the
NORTHERN HEMISPHERE is TILTED
AWAY from the SUN (Winter) and the
SOUTHERN HEMISPHERE is TILTED
TOWARD the SUN (Summer)
On JUNE 21st, NOTICE how the
SOUTHERN HEMISPHERE is TILTED
AWAY from the SUN (Winter) and the
NORTHERN HEMISPHERE is TILTED
TOWARD the SUN (Summer)
GLOBAL REGIONS
• POLAR REGION
– Area between the Arctic Circle Line and North
Pole, and Antarctic Circle Line and South Pole
• MIDLATITUDE REGION
– Area between the Circle Lines and the Tropics
Lines
• TROPICAL REGION
– Area between the two Tropics Lines
LATITUDE LINES AND GLOBAL REGIONS
POLAR
REGION
N POLE
ARCTIC CIRCLE
MIDLATITUDE
REGION
TROPIC OF CANCER
TROPICS
REGION
EQUATOR
TROPIC OF
CAPRICORN
ANTARCTIC CIRCLE
S POLE
HOMEWORK!!!
• Questions 1, 2, 4, 8 on page 502!!!
HOW IS ENERGY TRANSFERRED?
• As you already know, all
of the earth’s energy
initially comes from the
SUN, with its steamy
average temperature of
15,000,000oC, and its
energy output of 3.83 x
1023 kJ/s.
HOW IS ENERGY TRANSFERRED?
• Weather and climate patterns are based on
the transfer of energy between and within air
masses and water bodies.
• 4 METHODS OF ENERGY TRANSFER
– RADIATION
– CONDUCTION
– CONVECTION
– ADVECTION
1. RADIATION
• The transfer of energy in the form of WAVES.
• This type of energy can travel through A
VACUUM (empty space) as opposed to
through a MEDIUM (s, l, g).
• Examples of radiation waves include:
– UV, visible light, gamma rays, etc.
RADIATION . . .
ELECTROMAGNETIC SPECTRUM
• The complete set of radiation waves that can
travel through empty space.
Also See
Figure 1
on page
505
2. CONDUCTION
• The transfer of energy through the collision of
particles through solids.
• Occurs in conductive materials (i.e., metals).
• Small role in weather, bigger role in surface
heating.
CONDUCTION . . .
3. CONVECTION
• The transfer of energy by the VERTICAL
movement of particles in FLUIDS.
• Fluids are considered LIQUIDS or GASES.
• Important for weather patterns.
• http://channel.nationalgeographic.com/series/earth-thebiography/3130/Videos
CONVECTION . . .
4. ADVECTION
• The transfer of energy by the HORIZONTAL
movement of particles in fluids.
• Important for weather patterns.
• Ex: FOG
These forms of heat transfer do not
always act alone!
THE ALBEDO EFFECT
• Recall that ALBEDO is
an objects ability to
reflect LIGHT.
• LIGHT-coloured objects
have a HIGH albedo.
• DARK-coloured objects
have a LOW albedo.
HOW MUCH OF THE SUN’S ENERGY IS
REFLECTED?
• Refer to Figure 4 on p. 506 of your text.
• If we count the Sun’s energy as starting with
100 %, then:
– ____ is absorbed by land/oceans
– ____ is absorbed by clouds
– ____ is reflected by surface
– ____ is reflected by clouds
HEAT SINK
• Any object or material that ABSORBS energy
and becomes WARMER.
• A GOOD HEAT SINK is one that heats ups
SLOWLY, absorbing a LARGE amount of heat
before it heats up, such as WATER.
• A POOR HEAT SINK increases its temperature
QUICKLY when exposed to even a SMALL
amount of heat, but it LOSES heat just as
quickly, such as what happens with rocks, soil,
or sand.
HEAT CAPACITY
• A measure of the amount of heat energy
required to raise the temperature of 1 gram of
a substance by 1oC.
• See Figure 5 on page 506 for a list of some
heat capacities.
– WATER has a high heat capacity, meaning it has to
absorb a lot of heat to increase in temperature.
– METALS has a low heat capacity, meaning it
increases temperature with a relatively small
addition of heat.
HOMEWORK
• Q. 1, 2, 3, 4, 5, 6, 8 on p. 507.
THE EARTH’S SEASONS
THE EARTH’S SEASONS
• The earth rotates on its axis once a day in a
COUNTERCLOCKWISE direction.
• The earth also orbits around the Sun
elliptically and is tilted at an angle of 23.5o.
• The earth’s orbit around the Sun takes
approximately 364.25 days.
THE EARTH’S SEASONS
• Changes in the intensity of the Sun’s rays,
dues to daily and annual rotations, give us
SEASONS.
• SOLSTICE
– Points when the poles are tilted at their
MAXIMUM toward or away from sun.
• EQUINOX
– Sun’s rays strike Earth’s surface directly at
EQUATOR.
– Day and night of roughly EQUAL length
everywhere on earth.
THE EARTH’S SEASONS
• SUMMER SOLSTICE
– Northern hemisphere at MAXIMUM tilt TOWARD
sun. (YAY SUMMER!!!)
– JUNE 21st is longest day of year.
• WINTER SOLSTICE
– Northern hemisphere at MAXIMUM tilt AWAY
FROM sun. (BOO WINTER!!!)
– DEC 21st is shortest day of year.
THE EARTH’S SEASONS
• VERNAL EQUINOX (SPRING EQUINOX)
– Marks the first day of SPRING in the Northern
Hemisphere (AROUND MARCH 21)
• AUTUMNAL EQUINOX
– Marks the first day of FALL in the Northern
Hemisphere.(AROUND SEPTEMBER 21)
THE ATMOSPHERE
• http://video.google.ca/videose
arch?q=layers+of+the+atmosp
here&hl=en&emb=0&aq=f#
What is the Atmosphere?
DEFINITION:
• The blanket of air and water vapour that
surrounds the Earth.
• If the earth were an ONION, the atmosphere
would be like the ONION PEEL.
• It is about 500 km thick, containing 78% N , 21% O
, and some trace elements (ex: CO2, H2O, Ar).
LAYERS OF THE ATMOSPHERE
• Defined according to ALTITUDE, or elevation
above sea level.
• TROPOSPHERE
– 8-16 km altitude, layer closest to earth’s surface
– This layer is the most dense, meaning it contains
the most particles.
– Weather occurs in this layer.
– Temperature ranges from 20 to -50degrees
Celsius.
– The tropopause is on the upper end of this layer.
LAYERS OF THE ATMOSPHERE
• STRATOSPHERE
– 16-50 km altitude
– Very dry, temperature average is 10o degrees
Celsius.
– This layer contains ozone, responsible for
absorbing UV radiation from the Sun.
– Supersonic jets fly in this layer.
• MESOSPHERE
– 50-80 km altitude
– Temperature average is -75 degrees Celsius.
LAYERS OF THE ATMOSPHERE
• THERMOSPHERE (IONOSPHERE)
– 80-500 km altitude
– Temperature average is 30o degrees Celsius.
– Molecules and ions have high energy because
they are absorbing powerful waves from the SUN.
– On earth, we can see the Aurora Borealis in the
Northern Hemisphere and the Aurora Australis in
the Southern Hemisphere.
LAYERS OF THE ATMOSPHERE
• EXOSPHERE
– Outer layer converging with SPACE.
– Thin layer, made up mostly of H and He particles.
AURORAS
• The Sun ejects ionized particles into space that travel to the
Earth. Earth’s magnetic field deflects these particles toward
the poles, creating massive magnetic storms. They vibrate,
and when they return to the original state, light is emitted.
HOW DOES THE ATMOSPHERE SUPPORT LIFE?
1. Molecules such as O2, N2, H2O, CO2 needed
to support life processes.
2. Ozone, O3,needed to absorb harmful UV
rays.
3. Water cycle necessary to replenish water in
atmosphere, land, and water bodies.
4. Protection from meteors.
5. Maintenance of ideal Temperature.
6. Move energy around the Earth.
How did Life Begin?
• http://www.pbs.org/wgbh/nova/origins/
ATMOSPHERIC PRESSURE
• Defined as the pressure that air particles exert
as gravity pulls them toward the centre of the
earth
• Air pressure is greatest at sea level where air
is most dense (i.e., thick)
• Air pressure decreases with altitude.
– Thus, if you climb a mountain, the weight of the
air above you is less, and the pressure is less.
PRESSURE GRADIENT
• Another factor that affects air pressure is
whether air is rising or falling.
• A pressure gradient is a measure of these
changes in air pressure over set distance.
• Pressure gradients can be vertical or
horizontal.
HORIZONTAL PRESSURE GRADIENTS . . .
• Horizontal pressure gradients can be shown
on a map by joining points of equal
atmospheric pressure in concentric circles.
• They can be used to predict high and low
pressure areas and direction and strength of
winds.
Low wind speed (lines far apart)
High Wind speed (lines close together)
HOW DO WE MEASURE AIR PRESSURE?
• Air pressure is measured with an aneroid
barometer, (“aneroid” meaning “without
water).
– Figure 5, p. 512.
• Air pressure is measured in kPa, or
kilopascals. 1 kPa = 1000 Pa.
– If a barometer detects a :
• low pressure system (less than 101.3 kPa), this is a sign
of poor weather.
• High pressure system (greater than 101.3 kPa, this is a
sign of good weather.
HOW DO WE MEASURE AIR PRESSURE?
WINDS
• Wind is the movement of air in the
atmosphere.
– Some winds are local while others are prevailing.
• Local winds occur in a fairly small region.
• Prevailing winds are wind patterns that affect
large regions around the world.
PREVAILING WINDS
• In the early 1800s, SAILORS discovered that, in
certain areas, the winds blow in the same
direction all of the time.
THE CORIOLIS EFFECT
• The change of DIRECTIONof a moving object
in a constantly rotating system.
• The rotation of the EARTH deflects moving air
AND water to the RIGHT of its initial direction
in the Northern Hemisphere (opposite in the
Southern Hemisphere).
– Note:
• This direction of deflection is from the viewpoint of the starting
position of WHAT IS BEING DEFLECTED (ex: plane, wind, etc.).
– FIGURE 2 - pg. 517
– FIGURE 1 - pg. 525
THE CORIOLIS EFFECT
• http://www.classzone.com/books/earth_science/terc/content
/visualizations/es1904/es1904page01.cfm
• http://www.youtube.com/watch?v=mcPs_OdQOYU
THE CORIOLIS EFFECT
THE CORIOLIS EFFECT
HOMEWORK!!!
• 13.4 - Page 513, # 7, 8, 9
• 13.6 – READ section first, then answer Page
519, # 1, 2, 3, 4.
Prevailing Winds in the Northern Hemisphere
• Prevailing Winds help distribute energy and
moisture around the globe.
• TYPES IN NORTHERN HEMISPHERE
– Polar Easterlies
• Cold easterly winds blow from the poles to 60 degrees.
– Mid-Latitude Westerlies
• Warm, moist winds blow from the west
• NEWFOUNDLAND is affected by these.
– North East Trade Winds
• Winds that blow toward the equator
JET STREAMS
• Fast moving riversof air that race across the high altitude
sky, sometimes at speeds as high as 400 km/h.
• Jet streams occur about 7000 m up in the upper regions of
the troposphere.
• They consist mostly of westerly winds, and are caused by
strong differences in pressure and temperature.
• Air at the equator is thickerand moves from high to low
pressure areas (i.e., N or S of the equator).
• Jet streams can be thousands of miles long, hundreds of
miles wide, but only a mile or so deep.
JET STREAMS
• Pilots can reduce flight time by hitching a ride on a jet stream.
• Long lines of clouds often indicate the presence of a jet
stream.
THE HYDROSPHERE
• Water covers 70 % of the Earth’s surface, or
320 million cubic miles.
• The hydrosphere is all the water that exists on
the planet. It includes water in:
– Oceans
– Rivers
– Lakes
– Aquifers
– Glaciers/ice
– Atmosphere
WATER DISTRIBUTION
• 97.5% is salt water, 2.5% is fresh water.
• Most of our fresh water supply is trapped in polar ice caps
(87.3%).
• Canada is rich in fresh water resources, having 10% of the
total world supply.
THE HYDROLOGICAL CYCLE
• Water is cycled through air, land, and water bodies.
• Important processes that occur in the water cycle
include:
– EVAPORATION:
– CONDENSATION:
– TRANSPIRATION:
– SUBLIMATION:
– DEPOSITION:
– INFILTRATION:
– PRECIPITATION:
liquid to gas
gas to liquid
evaporation from leaves
solid to gas
gas to solid
seep into ground
rain, snow, hail, sleet
THE HYDROLOGICAL CYCLE
MAJOR OCEAN CURRENTS
• Oceans have a HUGE effect on weather
patterns. Here are just a few of the ways water
is significant in this regard:
– Oceans are heat sinks since most of the sun’s
direct rays hit water.
– If water is warm, air above it is warm, meaning
lots of moisture. If water is cold, air above it is
cold.
– Warm water is constantly moving from the
equator to the poles.
– Cold water is constantly moving from the poles to
the equator.
MAJOR OCEAN CURRENTS
• Which ones influence NEWFOUNDLAND
weather? __________________________
NEWFOUNDLAND AND
LABRADOR
WHAT CAUSES OCEAN CURRENTS?
•
•
•
•
•
•
Convection currents
Winds across oceans
Earth’s rotation
Shape of continents
Heat capacity of Water
Amount of salt in oceans
FYI – Just for FUN
• In 1992 a container ship in the middle of the Pacific Ocean
lost 29 000 bath tub toys over the side. Rubber duckies
started washing ashore all over the west coast of North
America.
• In 1990 in a similar type accident 80,000 pairs of Nike shoes
were swept off a Korean ship headed for the United states.
Nike shoes started showing up from Hawaii to Oregon and as
far north as Alaska.
• These two accidents provided valuable information to
oceanographers regarding ocean currents
HOMEWORK!!!
• P. 524, # 3,4,5
• P. 527, # 1, 4, 6
CLOUDS
• Clouds are a collection of water droplets that
has become dense enough to be visible.
Water evaporates and cools as it rises, and
condenses into clouds.
• They are important indicators of weather
patterns.
• Clouds can be grouped according to how they
form, how they are shaped, whether or not
they will lead to precipitation, and how high
they are.
3 TYPES OF CLOUD FORMATION
• 1. CONVECTION CLOUDS
• 2. OROGRAPHIC CLOUDS
• 3. FRONTAL CLOUDS
1. CONVECTION CLOUDS
• Convection clouds form when warm air near
heated surfaces such as the Earth gain energy
from these sources.
• As this warm air rises in heat, it expands and
carries water vapour into the atmosphere.
• The water vapour cools in the upper
atmosphere, forming a convection cloud.
• These clouds are often “puffy”.
1. CONVECTION CLOUDS
Something else puffy!
2. OROGRAPHIC CLOUDS
• Orographic clouds result from warm, moist air
ascending up a mountain, forming clouds on
the upwind slope as the temperature
decreases
• Thus, the near side of the mountain has
precipitation, and the far side of the mountain
is often dry.
2. OROGRAPHIC CLOUDS
• http://www.pbs.org/
wgbh/nova/kilimanja
ro/weather.html
3. FRONTAL CLOUDS
• Frontal clouds form when two
air
masses of different temperatures meet.
• Warm air masses generally are less dense and
contain more moisture than cold air masses,
thus rising over, or being pushed upward and
over, cold air.
• The rising air cools and condenses forming a
frontal cloud.
• Where the two air masses meet, this leading
edge is called a FRONT.
3. FRONTAL CLOUDS
3. FRONTAL CLOUDS
GROUPS OF CLOUDS
• BASED ON SHAPE
– CUMULUS clouds, from a term meaning “pile” or
“heap”, referring to a TALL CLOUD
– STRATUS clouds, from “stratum,” or layer,
referring to low-level layered clouds.
• BASED ON PRECIPITATION
– NIMBUS clouds, from a term meaning “rain”,
referring to rain-bearing clouds
• BASED ON ALTITUDE
– LOW LEVEL: NO PREFIX (0 – 2000 m)
– MEDIUM LEVEL:
ALTO (2000-5000 m)
– HIGH LEVEL: CIRRUS (5000 + m)
CUMULUS CLOUD VS. STRATUS CLOUD
CLOUDS
Cumulonimbus
FOG
• Fog is a cloud that forms near the
ground.
• Although there are many different types of fog, it
basically forms such that water vapour, as it
condenses, attaches
itself to little particles such as
dust specks.
• Some types of conditions that cause fog include
heat rising from the Earth’s surface and cooling
rapidly, warm air passing over snow, and warm
ocean air meeting cold ocean air.
FOG
HOMEWORK:
• P. 534 - # 2, 4,
• P. 541 - # 27
• Read and be familiar with Section 13.13, p.
536.
WHAT WOULD HAPPEN IF:
• http://www.pbs.org/wgbh/nova/elnino/anato
my/earthsweather.html
AND THAT’S ALL FOLKS!!!
Fine Print: Now study for your exam!