Download Factors affecting Temperature

Unit 2.4 - Weather
Factors affecting Temperature
Factors affecting Temperature

Temperature varies across the world
because of the variations in the following
factors:
◦
◦
◦
◦
◦
Latitude
Altitude
Distance from the sea
Cloud cover
Winds and ocean currents
Latitude

This refers to the
angular distance of
any point on the
Earth’s
surface
measured north or
south of the Equator.
Latitude
Is
temperature
higher at higher
latitudes or lower
latitudes?
 Why?

North Pole 90ºN
66½ºN
High Latitude
Middle Latitude
23½ºN
Low Latitude
0º
23½ºS
66½ºS
South Pole
90ºS
Latitude



The amount of heat
received by the
Earth’s
surface
decreases
as
latitude increases.
Areas with a tropical
climate are called “Low
latitudes” because they
are nearer the equator.
The average annual
temperature is 26.5ºC.



Areas
with
polar
climate are called “high
latitudes.
Temperatures in these
latitudes are never
warm.
The
average
temperature of the
warmest month is
<10ºC.
Latitude – Reasons for variance 1
Along the Equator, the Sun’s rays strike
the Earth’s surface perpendicularly.
 This high angle of incidence causes the
solar radiation to be concentrated over a
smaller area, causing more intense heat
hence the equatorial region experiences a
higher temperature.

Latitude – Reasons for variance 1
At the higher latitudes, the Sun’s rays
strike the Earth’s surface at smaller angles
of incidence.
 This causes the solar radiation to be
spread over a larger area, hence the
higher latitudes experiences a lower
temperature.

Latitude – Reasons for variance 2
About 50% of the solar energy that
reaches the atmosphere's upper layers are
absorbed by oxygen, ozone and other
molecules before it reaches the surface.
 More solar energy would have been lost
at the higher latitudes as the Sun’s rays
need to travel over a greater distance
through the atmosphere before reaching
the Earth’s surface.

short
long
Factors affecting Temperature

Temperature varies across the world
because of the variations in the following
factors:
◦
◦
◦
◦
◦
Latitude
Altitude
Distance from the sea
Cloud cover
Winds and ocean currents
Altitude
Altitude refers to the
height of a point in
relation to the sea
level.
 Temperature
are
quite different at
different altitudes.

Temperature
decreases
as
altitude increases.
 Temperatures
generally decrease by
6.5°C with every
1000m increase in
altitude.
 This
decrease in
temperature is called
lapse rate.

Based on the
location
of
Quito, Ecuador,
what type of
climate do you
think it should
have?
What
about
Guayaquil,
Ecuador?
Quito, Ecuador
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
14
14
14
15
14
14
14
14
14
14
14
14
Nov
Dec
Guayaquil, Ecuador
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
27
27
28
28
27
25.5
25
25
25.5
25.5 26
27
Altitude – Reasons for variance 1
About 45 % of the sun’s energy is directly
absorbed by the Earth’s surface, which in
turn radiates this back as heat.
 Temperature falls with altitude due to the
increased distance from the earth’s
surface – which is acting as a source of
heat.

Altitude – Reasons for variance 2



The atmosphere consists of water vapour
and other gases which absorb heat from the
Sun.
Due to the force of gravity, there is a higher
concentration of atmospheric molecules at
or near sea level hence most of the Sun’s
heat is absorbed at that level.
In addition, the same atmospheric molecules
are warmed by heat radiated from the
Earth’s surface hence temperature is higher
at the lower altitudes.
Factors affecting Temperature

Temperature varies across the world
because of the variations in the following
factors:
◦
◦
◦
◦
◦
Latitude
Altitude
Distance from the sea
Cloud cover
Winds and ocean currents
Distance from the sea
This refers to how
far away from a large
body of water an
area is located.
 Land and water react
differently to solar
heating which in turn
exerts
a
strong
influence on the
atmosphere.

Seas and oceans take
a longer time to heat
up, but once heated
up will retain heat
longer.
 Land, on the other
hand, heats up very
quickly and loses
heat quickly.

Distance from the sea


Interiors
will
be
hotter in the summer
and colder in winter
than
maritime
regions at the same
latitude.
The ocean significantly
moderates
the
temperatures of the
coastal
(maritime)
regions of a continent.

The ocean will have a
cooling
effect
in summer and a
warming effect in winter.
◦ These areas tend to have
smaller annual temperature
ranges.

Places
inland
are
generally
warmer
in summer and cooler
in winter.
◦ These areas tend to have
larger annual temperature
ranges.
Reason for variance

Maritime effect: the effect that oceans have on
the climate of coastal areas.
◦ During summer, the air over the sea is cooler
than the air over the land as land heats up quickly
while the sea heats up slowly.
◦ The cooler air over the sea helps lower the
temperature of coastal areas, leading to cool
summers.
◦ During winter, the air over the sea remains
warmer than the air over the land as the sea
cools more slowly than the land, leading to
warmer winters.
Reason for variance

Continental effect: the effect that
continental areas have on the climate of
inland areas far away from the sea.
◦ During summer, the air over the land heats
up quickly leading to warmer summers.
◦ During winter the air over the land loses
heat quickly leading to colder winters..
Factors affecting Temperature

Temperature varies across the world
because of the variations in the following
factors:
◦
◦
◦
◦
◦
Latitude
Altitude
Distance from the sea
Cloud cover
Winds and ocean currents
Cloud Cover – the effect
This refers to the
amount of clouds
over an area.
 Clouds influence the
amount of solar
radiation entering /
leaving an area.

The presence or
absence of cloud
cover affects how
high
temperatures
may reach during the
day and night.
 In this way it will also
affect
diurnal
temperature
range.

Cloud Cover – the effect 1



Temperatures
are
higher on days where
clouds are absent.
The absence of clouds
allows large amounts
of the sun’s energy to
reach the Earth.
This heats up the
Earth’s surface which
in turn heats the air
near
the
Earth’s
surface.



Temperatures
are
lower
on
nights
where clouds are
absent.
The absence of clouds
allows more of the
heat radiated from the
earth’s surface to
escape into space.
This
causes
temperatures to fall at
night.
Cloud Cover – the effect 2


Temperatures
are
lower on cloudy days.
Clouds reflect a large
portion of the sun’s
energy
(solar
radiation) back to
space.



Temperatures
are
higher
on
cloudy
nights.
Clouds absorb more
of the heat that is
radiated from the
Earth’s surface and
prevent
it
from
escaping into space.
This allows nighttime
temperatures
to
remain high.
Places with no cloud cover



Desert areas have little to
no cloud cover, due to low
humidity in the air.
The land gets very hot
during the day and very
cool at night.
Such areas experience a
larger difference between
daytime and nighttime
temperatures.
Places with dense cloud cover



Tropical areas have dense
cloud cover, due to high
humidity.
Clouds
absorb
heat
radiated from the Earth’s
surface during the day and
night.
They will experience a
smaller difference between
daytime and nighttime
temperatures.
Cloud Cover – the effect 3
Factors affecting Temperature

Temperature varies across the world
because of the variations in the following
factors:
◦
◦
◦
◦
◦
Latitude
Altitude
Distance from the sea
Cloud cover
Winds and ocean currents
Winds and ocean currents



The general circulation of the
ocean
is
a
significant
mechanism of global heat
transfer.
Ocean currents are able to
transfer heat from warm
(low) latitudes to cooler
(higher) ones.
Winds blowing over these
currents in turn transfer the
heat (or cold) to the adjacent
coastal regions.

Major surface ocean currents
move warm water from the
equatorial regions toward the
poles, and bring cool water
from the poles back toward
the equator.

In each of the main ocean
basins, warm water is moving
toward the poles off the east
coasts of continents (making
adjacent land warmer) while
cool water is moving toward
the equator off the west
coasts of continents (making
adjacent land cooler).
WINDS AND OCEAN CURRENTS
The west coast of Britain is kept warmer in winter than
other places in similar latitudes by one such current of
warm water, the North Atlantic Drift (also known as the
Gulf Stream).
Durban and Port Nolloth are both found at 30°S and
at sea level, but have very different climates.
Durban’s temperatures are consistently warmer than
Port Noloth’s. This is due to the warm Mozambique
current flowing South past Durban and the cool
Benguela current flowing north past Port Nolloth.
These currents act to regulate the temperatures of
the places found near them.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Yr
Durban (°C)
24.3
24.5
23.7
21.9
19.5
17.5
17.2
18.2
19.4
20.5
21.9
23.3
21.0
Port Nolloth(°C)
16.3
16.5
16.0
15.2
14.5
14.2
13.1
12.9
13.3
14.1
15.2
16.1
14.8
The Gulf Stream
Hopedale, Newfoundland and Labrador
Latitude = 55.45o N
Avg.Temp. = -2.0o C
Stornoway, Scotland
Latitude = 58.22o N
Avg.Temp. = 9.4o C