Download Weather and Climate Review

Weather and Climate Review
Climate is what you can expect the weather to be like over a long
period of time
There are several things that determine what the climate will be:
How far is the place from the equator?
What season is it – is the area tilted away from the sun?
Are there warm or cold ocean currents nearby?
What is the altitude (metres above sea level)?
Is it on or near a large body of water, like the ocean?
Connected to this is – is it inland (continental or maritime)
What are the prevailing winds in the area?
Why are there different climates in
different parts of the world?
Water
 Altitude
 Latitude
 Prevailing winds
 Ocean Currents
 Contintentality

There are two ideas here that are
important!
 Water
takes a long time to warm
up, but water cools down very
slowly
 Land
warms up quickly, and also
land cools quickly
Ocean Currents

Prevailing
winds of the
earth
What is Climate?


Climate is more than "the average state of the atmosphere"
because a complete climate description should also include
variations and extremes to accurately portray the total character
of an area.
The most important elements in climate descriptions are
temperature and precipitation inasmuch as they have the
greatest influence on people and their activities and also have
as important impact on the distribution of vegetation and the
development of soils.
Koppen Climate Classification
What is the difference between
Koppen’s climate classification
zones and a biome?

A biome is related to the biological parts
within an area (plants and animals)

Whereas Koppen’s climate classification
system uses temperature and
precipitation and is related to the
environment (which supports plants and
animals)
What causes wind systems?
The necessity to equalize pressure on the earth’s
surface
 Rising air in low pressure areas (warm air)must be
replaced by air flowing in from high pressure areas
(cold air)
 Winds always blow from areas of high pressure into
areas of low pressure
 The greater the difference in pressure, the greater
the velocity
 This difference is called the pressure gradient
(see weather and air pressure video)

Global Winds
Coriolis Effect
Surface Winds

Remember: Air flows from HIGH to LOW pressure!
So in a low pressure system the winds flow counter
clockwise= into the centre where the pressure is the
lowest.

In a high pressure system the winds flow
clockwise=away from the centre where the pressure
is the highest.

This is reversed in the southern hemisphere.
The Jet Stream
Sea breeze
Land Breeze
Air Masses Over North America
QuickTime™ and a
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What is a weather front?

A weather front (or “front”) is a boundary
separating two masses of air of different
densities
Types of Fronts
Practice
1) If a wind is called a westerlie it is flowing from
the__________________.
2) There is little wind near the equator and this is known
as the ____________.
3) If an air mass is composed of cold dry air it is
_______________________.
4) If an air mass is composed of warm dry air it
is______________________.
5) The coriolis effect causes winds in North America to
flow ___________.
6) All winds flow from _____________ to
_________pressure.
7) True or False. Areas located North of the jet
stream will be colder than areas south of it.
How are water bodies and land
masses connected?
Water bodies provide sources of
moisture for the land masses of the
world
 In general, locations near water bodies
experience wetter climates than
locations found far from water bodies
(Continentality)

Are there any other exceptions?
Areas that experience offshore winds
for much of the year get dry winds that
blow from the land to the water
 Even in coastline locations, these winds
can cause desert conditions
 Another exception is areas that receive
a lot of cold air due to cold ocean
currents - this air does not evaporate,
nor hold much water vapour

Altitude

Under normal atmospheric conditions,
air temperatures decrease as altitude
increases
What is this relationship called?

This decrease in air temperatures with
increased elevation is called the
Environmental lapse rate

On average, the Environmental lapse
rate equals 6.4 * C for every 1000m
What is Albedo?

The amount of radiation that is reflected
off a surface is called the Albedo

It can be thought of as the amount of
solar energy that is not absorbed

Dark surfaces have a lower albedo than
lighter surfaces (think about how
reflective snow is)
Mountains
What is the difference between
cloud and fog?

If it is on the surface of the earth, it is
fog; if it is above the surface, it is a
cloud

Condensation occurs when air goes
from warmer to colder

When warm air is moving horizontally, it
is called Advection fog
Ocean Currents
Why is Ocean Circulation
Important?

Transport ~ 20% of
latitudinal heat
 Equator to poles
 Transport nutrients
and organisms
 Influences weather
and climate
 Influences commerce
The Air Above Ocean Currents

Water brings with it the characteristics it
possesses.

What do we mean by that?

Warm currents make the air above them
warmer,while cool currents cool the air above
them
What is the Gulf Stream?

A strong ocean current that moves
warm water Eastward across the
Atlantic from the Eastern U.S. to Europe
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Surface and Deep-Sea Current
Interactions
Unifying concept: “Global Ocean Conveyor Belt”
http://seis.natsci.csulb.edu/rbehl/ConvBelt.htm
Urban Areas

This heat is absorbed during the day (as
short wave radiation) and then released
slowly at night (as long wave radiation)

Further heat is given off by the
presence of factories and increased car
use within the cities
Scattered Radiation
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This is called the Wind tunnel
effect
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Urban Areas

In addition, urban areas have high rates of particulate
matter pollution

Thick, black smoke belching out of the exhaust pipes
of vehicles. Swirls of dust picked up by the wind. Ash
and soot coming from your campfire. These are all
examples of particulate matter (PM). PM is the term
used for solid or liquid particles emitted to the air.
Some particles are large enough to be seen, and
others are so small they can only be detected with an
electron microscope.
Urban Areas

This increase of heat in urban areas
compared to rural areas nearby is
referred to as the urban heat island

Some cities have been measured at
7*C to 10*C more than surrounding
rural areas
Reduction Strategies

Reduce emissions and energy consumption
 Use reflective pavements (ie. not asphalt)
 Build green roofs on buildings
 Plant more trees and have more parks
 Educate people about this topic
 Implement government strategies that encourage the
reduction of the effect of Urban Heat Islands
What instruments are used to
measure the following weather
components?

Air pressure?

Wind speed?

Temperature?
Fronts

A front is the boundary between two
different air masses

Most of the weather affecting our region
is the result of cold, dry, polar air
coming into contact with warm, humid,
sub-tropical air
Cold Front

Cold fronts are those where cold air
replaces warm air.
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Warm Front

A warm front is where warm air
replaces cold air.
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Occluded Front

An occluded front forms when a cold front
meets the cool air that was ahead of the
warm front
 The warm air rises are these air masses
come together
 They usually form around areas of low
pressure, resulting in precipitation
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Stationary Front

Stationary Front - a boundary between
2 different air masses, neither of which
is strong enough to replace the other
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Cyclones and Anti-cyclones

Zones of low pressure are called
cyclones

Zones of high pressure are called anticyclones

Remember that air pressure always
goes from high pressure to low pressure
Cyclones
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Anticyclones
Isobars

Isobars - the lines joining points of equal
pressure at the earth’s surface
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Types of Clouds

Cumulus (vertical development)

Cumulonimbus (vertical development)

Stratus (low clouds)

Cirrus (high clouds)
Types of Precipitation

Orographic

Frontal/cyclonic

Convectional
What is the dew point?

The dew point temperature is the
temperature at which the air must
become cooled in order to become
completely saturated with water vapour

If the air is cooled to the dew point
temperature, it will become saturated
Weather Station Model
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Hurricanes and Tornadoes: How
Do They Differ?
Location
 Size
 Duration
 Season of Occurrence
 Distinctive Hazards
