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

– 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

MIDLATITUDE

REGION

TROPICS

REGION

ARCTIC CIRCLE

TROPIC OF CANCER

EQUATOR

TROPIC OF

CAPRICORN

ANTARCTIC CIRCLE

N POLE

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-the-

biography/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/videos

earch?q=layers+of+the+atm

osphere&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.

High Wind speed (lines close together)

Low wind speed (lines far apart)

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/cont

ent/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: liquid to gas

– CONDENSATION: gas to liquid

– TRANSPIRATION: evaporation from leaves

– SUBLIMATION: solid to gas

– DEPOSITION: gas to solid

– INFILTRATION: seep into ground

– PRECIPITATION: 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/kilimanj

aro/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/anat

omy/earthsweather.html

AND THAT’S ALL FOLKS!!! Fine Print: Now study for your exam!