Transcript Unit 3 lesson 1-3

Ch 15 the Atmosphere
https://youtu.be/3CerJbZ-dm0
I. Characteristics of the Atmosphere
A. Composition
1. Atmosphere= mixture of gases that surrounds Earth
2. ~78% nitrogen gas released from the breakdown of dead plants & animals
and from volcanic eruptions
3. ~21% oxygen gas from plants and phytoplankton
4. ~1% is argon, carbon dioxide, water vapor, &other gases
5. Atmospheric water can be in liquid, solid (ice/snow) or mostly in vapor
B. Atmospheric Pressure and Temperature
1. As altitude increases, air
pressure decreases
2. Gravity pulls gas molecules to
the surface causing air pressure
 Air pressure= measure of the
force with which air molecules
push on a surface

Strongest at Earth’s surface
3. Atmospheric composition affects
air temp
 Parts are warmer b/c the
particles in the air absorb solar
energy
C. Layers of the atmosphere
1. Trophosphere= “tropo-” means
turning or change
a. Lowest layer lying next to Earth
b. Densest layer
c. ~90% of the atmospheres total
mass
d. Life is in this sphere
e. Temperature differences causes air
to constantly mix
2. Stratosphere= “layer”
a. Gases layer and do not mix like in
the troposphere
b. Air is very thin with little moisture
c. Lower portion is very cold (-60°C)
d. Ozone layer absorbs ultra violet
rays warming the top layer
https://youtu.be/BbwEF6xvlVg
3. Mesosphere= “middle” and
coldest layer
 Temps as low as -93°C at the
top
 Does not have ozone to absorb
ultraviolet rays which warm the
air
 Higher than aircraft can fly and
lower than satellites can orbit=
hard to study
4. Thermosphere= “Heat”
a. Nitrogen and oxygen atoms
absorb heat energy
b. Can reach 1000°C or higher
c. Heat is measure of the speed
of particles
d. Does not feel hot because
there are not very many
particles to collide to transfer
the thermal energy
5. Ionosphere: Part of the
Thermosphere
a. Home of the auroras
b. Gas particles in the thermosphere
become electrically charged
c. Electrically charged particles are ions=
ionosphere
d. Ions radiate energy as shimmering
lights
e. Oxygen= greenish yellow or red
f. Nitrogen= bluish
g. Am radio wave waves reflect off of the
ionosphere & are sent back to Earth
h. Can be considered part of
thermosphere
D. Greenhouse Effect & Life on Earth
1. ~70% of the radiation that enters Earth’s atmosphere is absorbed by the Earths
surface & clouds
 This energy warms the planet
2. The atmosphere acts like a blanket keeping some of the heat in
3. Greenhouse effect= process by which gasses in the atmosphere absorb thermal
energy & radiate it back to Earth= NATURAL PROCESS
 Water vapor
 CO2
4. Solar energy comes in but not all is allowed to leave
5. Life on Earth WOULD NOT be possible without the greenhouse effect
6. Radiation balance= balance
between incoming energy and
outgoing energy
 Amount of energy coming in from
space should be ~equal to the
amount of energy returning to space
7. Global warming= gradual increase in
the average global temperatures
 Slight increase in global temps over
the last 100 years
 Scientist debate whether the increase
is due to increased fossil fuel usage
from humans
 Additional gases could cause less
thermal energy to be released back
into space https://youtu.be/DrRZsUwkHrM
II. Energy Transfer
A. Energy & Temperature
1. Temperature= a measure of the average kinetic
energy of particles
 Faster the particle the more energy
2. Thermal energy= the total kinetic energy of particles
https://youtu.be/gNM_9etcJT0
 Depends on the number of particles
 The more particle= higher thermal energy
3. Thermal expansion= an increase in volume that results
from an increase in temperature
 As a substance heats, the particles move further apart
=expansion
Exception= water which also expands when it cools
https://youtu.be/IHhvaUdWfDI

4. Density= mass per unit volume
 When substances expands their volume increases BUT the

mass stays the same= density decreases
This is how hot air balloons fly
B. Heat
1. Heat= the energy that is transferred between objects
that are at different temperatures
2. Heat always transfers from warm to cold
3. Specific heat=the property by which materials
become warmer or cooler at different rates
 Water has a high specific heat so it warms slow but
also cools slow
B. Heat Transfer
1. Radiation= the transfer of energy as electromagnetic waves
a. Earth receives the suns radiant energy
b. Radiant energy is absorbed by the atmosphere, land and water
and changed into thermal energy
2. Conduction: transfer of thermal energy through a material
a. Always from warm to cold
b. Air is warmed by coming into direct contact with the warm surface
of the Earth- not a major way to heat the atmosphere
3. Convection: transfer of thermal energy by the circulation or movement of a
liquid or gas
a. Most thermal energy in the atmosphere is transferred through convection
b. Hot air is less dense= rises
c. Cool air more dense= sinks
d. The circular movement or warm & cool air rising and falling creates a convection
current
e. Ovens can bake faster using a convection current
III. Global Winds and Local Winds
A. Air Movements
1. Wind= movement of air caused
by the differences in air pressure
https://youtu.be/xCLwbqmacck
 Greater the pressure difference
the faster the wind moves
2. Air rises at the equator and sinks
at the poles because of unequal
heating of the Earth
a. Equator receives more direct
solar energy
b. Warm, less dense, low pressure
air rises and moves towards
poles
c. Colder, more dense, high
pressure air sinks and moves
towards the equator
3. Convection cells= large circular
patterns that air travels in
https://youtu.be/DHrapzHPCSA
a. Hadley cells:
 located between 0-degrees and 30degrees latitude in both hemispheres
 As air warms it rises causing the low
pressure zones
b. Ferrel cell:
 located between 30-degrees and 60degrees latitude in both hemispheres
 where air sinks at 30-degrees latitude
and travels on the Earth’s surface
towards the poles
 When the air reaches 60-degrees
latitude it rises and flows back
towards the equator
6. Coriolis effect
https://youtu.be/i2mec3vgeaI
a. Apparent curving of the path of winds
and ocean currents due to the Earth’s
rotation
b. Northern hemisphere winds turn to the
east
c. Southern hemisphere winds turn to
the west
B. Global winds: patterns of circulation every 30° of
latitude
https://youtu.be/DOtKdyYdf5c
1. Polar easterlies: wind belts that
extend from the poles to 60°
latitude in both hemispheres
 Carry cold arctic air
 Producing snow & freezing weather
2. Westerlies: wind belts found
between 30° & 60° latitude in both
hemispheres
 Carry moist air
 Produces rain & snow
3. Trade winds: blow from 30° almost
to the equator
 Early traders used this wind to curve
to sail from Europe to Americas
4. Doldrums (ITCZ: Inter tropical
convergence zone)= very little wind
between the trade winds and the
equator
 “sluggish” “dull”
 Warm rising air creates low pressure
5. Horse latitudes: 30° N & 30°S areas
of weak winds
 Got the name because sailors would


throw the horses over to save
drinking water
Area of very little precipitation
Most of the world’s deserts are
located at this latitude
6. Jet streams: narrow belts of high
speed winds that blow in the upper
troposphere & reach max of 400m/h
 Affect movement of planes &
weather (storms)
C. Local winds
1. Caused by the heating and
cooling of air
2. Warm air rises and cool air sinks
3. Land heats fast than water so
during the day wind flows from
ocean to land
 At night it flows from from land
to ocean
4. Mountain breezes are caused
by air moves down the mountain
slope to the valleys as it cools
Wind challenge
 https://youtu.be/fNudnI5tzf8
 https://youtu.be/qYH6QiaMw
Eo
 https://youtu.be/PfvqGwoZAq
8 Denmark
 https://youtu.be/Fep4CSRore
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