Download Ch 17 - The Atmosphere

Ch 17 - The
Atmosphere
Vocab Charts (Example)
Word
Definition
Weather
the state of the
atmosphere at a
given time and
place
Picture
Weather = the state of the
atmosphere at a given time
and place (constantly changing)
- controlled by Earth’s motions
& energy from the sun
Climate = the given
weather conditions
of an area over
many years
- covers average
rainfall, avg.
temperature, avg.
humidity, avg. wind
direction, avg. air
pressure etc…
Composition of the Atmosphere
• Earth’s early
atmosphere thought to
be created by large
volcanic eruptions of
gas
• Oxygen was not present
in the atmosphere until
~2.5 billion years ago
• Current atmosphere constantly exchanging
gases with oceans and life on Earth
• Current composition of atmosphere:
78% Nitrogen
21% Oxygen
0.93% Argon (inert gas)
0.039% Carbon Dioxide
Composition cont…
Also present in atmosphere =
water vapor, dust, ozone, and
pollution
–Water vapor makes up clouds &
precipitation
– Ozone (O3) is
concentrated between 10
-50 km from surface
• Block harmful Ultraviolet
(UV) rays
– Air pollution is mainly
from car exhaust
Structure of Atmosphere
- There is no distinct
boundary between
the atmosphere and
outer space, but it
does thin as you
increase in altitude
The atmosphere is
divided into 4 layers
based on temperature:
1. Troposphere =
temperature decreases
as you increase altitude
- Extends from surface to
~12 km
- All weather occurs here
2. Stratosphere = slight
increase in temperature
- Extends from 12km to ~50
km
- Contains the Ozone Layer
(absorbs UV to increase
temperature)
3. Mesosphere =
temperatures
decrease with altitude
- No definite upper limit
- Temperatures near
-90ºC
4. Thermosphere =
temperatures
increase due to
absorption of high
energy solar radiation
- No definite upper limit
Troposphere, Stratosphere
Earth’s Orientation
Seasonal changes occur because Earth’s
position relative to the sun continually
changes as it travels along its orbit.
Solstices and Equinoxes
Solstices
• Summer Solstice: First official day
of summer. Northern Hemisphere
leaning 23.5 degrees towards sun.
• Winter Solstice: (opposite side of
the orbit) December 21 or 22nd.
N.H. leans 23.5 degrees away from
the sun.
Equinoxes
• Midway between solstices.
• September 22nd or 23rd date
of Autumnal Equinox.
• March 21st or 22nd date of
Spring Equinox
Heating the Atmosphere
Within the atmosphere heat is transferred 3
ways:
1. Conduction = transfer of heat
through direct contact of
molecules
- heat flows from the hotter object
into the colder object
2. Convection = transfer of heat by
mass movement or circulation
within a substance
- heat from below (ground)
conducts heat near the base of
the atmosphere, the air rises &
expands causing cooler air to sink
= circulating air patterns within the
atmosphere
Convection
3. Radiation = heat is radiated (travels by
waves) from the sun and hits the atmosphere
- some radiated energy is absorbed and some is
reflected (bounced) back into space
~30% is reflected back into space
~50% is absorbed by land & sea
~20% is absorbed by clouds &
atmosphere
Radiation
Greenhouse Effect
• Earth’s atmosphere naturally
absorbs heat from the sun because
of water vapor & carbon dioxide
composition
• The atmosphere also traps heat
(infrared waves) near the Earth’s
surface
• Without this natural greenhouse effect,
Earth’s temperature would be much
colder (uninhabitable for humans)
• Increased levels of carbon dioxide
(mainly from car exhaust) increases the
atmosphere’s ability to trap heat =
Earth’s temperature is getting warmer
Global Warming
• Increased levels of
CO2 (mainly from car
exhaust) which
increases the
atmospheres ability
to trap heat.
• Earths’ Temperature
is getting WARMER
Why do temperatures vary
so much on Earth?
5 Reasons:
1. Latitude (distance from the equator)
– Differences in amount of solar radiation
received
– Variations in the angle of sun’s rays
– Length of daylight
2. Heating of land & water
- Land heats more rapidly and to higher
temperatures than water
- Land also cools more rapidly and to
lower temperatures than water
- Cities near water have a smaller daily
temperature change compared to cities more
inland
3. Altitude
- The higher the altitude,
the colder the
temperatures
Continued….
4. Geographic Position (related to
prevailing wind direction)
- A town on the ocean, with the wind blowing
in from the ocean, will, experience moderate
temperatures (cool summers & mild winters)
EX: S. California
- A town near mountains and the ocean will
experience moderate temperatures & increased
rain because mts act like a barrier to wind &
rain
EX: Seattle, Washington
5. Cloud Cover
- Clouds reflect a significant amount of
solar radiation
- Cities with lots of cloud cover will have
significantly lower temperatures than a
location with sunny weather
- Clouds at night keep heat trapped at
surface, clear nights allow heat to escape into
space and make chilly nights
Albedo- fraction of total radiation
that is reflected by any surface
(Clouds have high albedo bc
large portion of sunlight is
reflected back to spaces.
Word Distribution of
Temperature
• Map used to study global
temperature patterns and
effects of factors on
temperature such as
latitude, distribution of land,
and water and ocean
currents.
• Isotherms- are lines that
connect points that have
same temperature
Ch 17 Final Assignment
THIS IS WORTH 25 POINTS!
Page 499 - 500
#1, 2, 4, 6, 8 = write out both question and answer
#11, 12, 13, 17, 18, 27 = write out only answers in
complete sentences
Vocabulary Words
Autumnal Equinox
Convection
Mesosphere
Radiation
Spring Equinox
Summer Solstice
Troposphere
Conduction
Greenhouse Effect
Ozone
Reflection
Stratosphere
Thermosphere
Winter Solstice