Download LOW PRESSURE

Energy Transfer
 Source of all energy: Sun
 Fate of energy Earth receives from sun:
 reflected
back into
space
 absorbed by
atmosphere
 absorbed by
land and
water
Energy Transfer
 Absorb solar energy: vegetation
and dark surfaces.
 Dark Surfaces
 Reflect solar energy: sand, snow,
and water.
 Light Surfaces
Energy Transfer
 Types of energy transfer:
1. Radiation – transfer of energy by
electromagnetic waves
 Travels through space
 Comes from sun
2. Conduction –transfer of
energy when molecules
bump into each other
 Ex: touching a hot stove
Energy Transfer
3.Convection – transfer of heat due to
density differences
 Warm air is less dense.
 Less dense air rises.
 Convection currents form in atmosphere,
oceans, and the mantle.
Quick Review…
Radiation, Conduction, or Convection?
 Sunlight filtering through Earth’s Radiation
atmosphere
 Warm magma rises in the asthenosphere Convection
 You burn your hand if you touch a hot
Conduction
stove
 Warm water rises in the oceans
Convection
 Light from a lamp in your house
Radiation
 A metal spoon gets hot if left in a pot of
Conduction
cooking food
Heat Transfer Foldable
 You will have 20 mins to
complete the following:
Step 1: 
1. Fold a piece of paper
Hot Dog and divide it
into thirds.
2. Label the front:
Conduction/Convection/
Radiation
3. Inside Left is a
Definition.
4. Inside right is a picture
on how it relates to the
atmosphere.
This will be stapled to the back of your
“Origins of the Atmosphere Notes”
Step 2:
Define
Step 3:
Illustrate
Weather versus Climate!
Why does Topic
the wind blow?
Pressure,
Wind,
Weather
Facts
Air stops rising when it
meets air of equal
density, then diverges
at high level to produce
more wind which
eventually sinks
elsewhere to complete
the circulation cell
Pressure, Wind and Weather
Systems
WINDS are horizontal flows of air;
�
winds blow from areas of high
pressure to areas of low pressure
(nature tries to equalise pressure)
PRESSURE describes the tendency
of the air to rise or to sink at any
given place or time.
�
Air tends to rise or sink as a result
of its density.
�
Insolation
Air heated by
contact with ground
expands; becomes
less dense and rises
Denser air
drawn in at low
level to replace
rising, less
dense air
Air density varies with altitude
but, at the ground level, air density
is governed by its temperature.
�
Thus, variations in radiation and
temperature control pressure and
wind.
�
LOW
PRESSURE
Sun heats up ground
Denser air drawn in at low
level to replace rising, less
dense air
GLOBAL PRESSURE & WIND
North Pole 90°N
Arctic circle 66.5°N
HIGH
Tropic of Cancer
23.5°N
Equator 0°
LOW
Tropic of Capricorn
23.5°N
Antarctic circle 66.5°S
HIGH
North Pole 90°N
ZONE of least heating produces
HIGH PRESSURE
ZONE of greatest
heating produces
LOW PRESSURE
ZONE of least heating produces
HIGH PRESSURE
GLOBAL PRESSURE & WIND
Global circulation depends on differential heating over the globe. The system is driven by strong
equatorial heating, causing LOW PRESSURE. Equatorial air rises, diverges and descends over the
tropics, where HIGH PRESSURE dominates; where it diverges at ground level. This tropical air blows
towards the equator, completing the equatorial cell, or towards the mid-latitides where it meets cold,
dense polar air blown out from the polar HIGH PRESSURE. These contrasting tropical and polar air
masses meet at the POLAR FRONT LOW PRESSURE BELT, where the warmer air is forced upwards by
the polar air. At high level, this air again diverges towards the pole or to the tropic.
Rising air diverges at the
tropopause, where a
permanent temperature
inversion results in
warmer air above.
POLAR HIGH
POLAR FRONT (LOW PRESSURE)
TROPICAL HIGH
EQUATORIAL (Inter-tropical convergence zone - ITCZ) LOW
High
CORIOLIS FORCE
Theoretical wind
which would result
solely from pressure
gradient
Actual wind
which blows, as
diverted by
Coriolis Force
Low
Pressure gradient wind blows from
high presure towards low pressure.
� The earth’s rotation diverts this
wind direction laterally. This force is
called the CORIOLIS FORCE.
� The Coriolis force diverts wind the
the right in the northern
hemisphere; to the left in the south.
� The effect is stronger at high
altitude where ground level friction
is less significant.
�
LOW
In the north, winds
blow clockwise out
from a high pressure.
(In the south, they blow
anti-clockwise).
HIGH
In the north,
winds blow anticlockwise into a
low pressure
system. In the
south, they blow
GLOBAL PRESSURE & WIND
POLAR HIGH PRESSURE
POLAR FRONT
MID-LATITUDE LOW
PRESSURE
INTER-TROPICAL
CONVERGENCE ZONE LOW PRESSURE
POLAR FRONT
MID-LATITUDE LOW
PRESSURE
TROPICAL HIGH
PRESSURE
TROPICAL HIGH
PRESSURE
POLAR HIGH PRESSURE
GLOBAL WIND BELTS (trade winds) are controlled by the major pressure belts, which
relate fundamentally to temperature. Regional wind systems (eg the Indian Monsoon)
relate to continental heating effects, and seasonal changes. Local winds relate to smaller
scale temperature contrasts (ie Aspect, Albedo, Altitude etc).
Identify five factors
that affect climate
and explain
how each
affects climate.
How does latitude
affect climate?
Temperature
As latitudeincreases
________, the average
annual temperature decreases
_________.
0°
Latitude
90°
How does closeness to a large
body of water affect climate?
Watermoderates
__________ the temperature.
Cooler
Warmerwinters.
_______ summers. _______
Cities A & B are located
at the same latitude.
City B is closer to a large body
of water.
Its temperature line is flatter
(moderated).
The leeward
sides of the
Adirondacks &
Catskills receive
much less
precipitation
The windward sides of the
Adirondacks & Catskills receive
a great deal more precipitation
How does the
Orographic Effect
affect climate?
cool, moist
Windward Side: ___________
warm, dry
Leeward Side: _____________
Page 14 of the ESRTs
We live in the troposphere.
Temperature decreases
with elevation.
During summer, temperature is strongly controlled by elevation -- cold at the higher
reaches of the Alaska and Brooks Ranges, and warmer in the lowlands.
How does elevation
affect climate?
Temperature
increases the average
As elevation _________,
annual temperature __________.
decreases
Elevation
How do ocean currents
affect climate?
Warm Currents: warmer climate
Cold Currents: cooler climate