Transcript Key Idea 18 Solar Energy

Key Idea #18
The sun is the major source of energy for
events that occur on the surface of the Earth.
http://hurricanetrack.com/jpegs/ingred1.jpg
The Sun and Weather
Nuclear reactions that take place in the sun produce
large amounts of heat and light.
aerospaceguide.net,shatters.net
From Solar Energy to Heat
http://www.youtube.com/watch?v=uO
WzNBXk3ss
The direct transfer of energy by electromagnetic
waves from the sun, is called radiation.
Heat is a form of energy
associated with the motion of
atoms or molecules.
The sun sends energy to the
Earth in the form of infrared
radiation which is transformed
into thermal (heat) energy after
it arrives on Earth.
The energy that heats Earth’s
atmosphere and surface comes
from infrared radiation from the
sun.
http://forces.si.edu/atmosphere/04_00_22.html
Only a small percent of light energy from the sun
that hits the Earth produces heat energy on Earth.
• Most of the sun’s
energy is either
reflected or
absorbed by
particles in the
atmosphere.
http://assets.panda.org/img/original/faq_1_3_fig_1.jpg
Earth’s Seasons
http://www.youtube.com/watch?v=Dui
QvPLWziQ
The heating of the Earth at any location is related to
the angle of the sun. (See book pgs 118-119.)
The hemisphere tilted
toward the sun receives
more direct sunlight and
experiences spring and
summer.
The hemisphere tilted
away from the sun
receives less direct
sunlight and experiences
fall and winter.
http://web.srv.cmes.utah.edu:8080/west/k12/EarthsTiltPic/view
Light energy from the sun is
changed into heat energy
when it is absorbed by land
and water on Earth’s surface.
The heat energy transfers
out of the ground or water
and heats the air above by
conduction.
radiation
conduction
http://www.shorstmeyer.com/gifs/dayheat.gif
Many of Earth’s surfaces reflect light energy away
from the Earth.
The color of the Earth’s surface
affects the amount of heat that
the Earth absorbs.
Light colored surfaces reflect
Dark colored surfaces absorb
The large amounts of light
energy that are reflected off
Earth’s surface can’t be used
directly as heat energy.
teachingboxes.org
Gases in the atmosphere that trap heat are called
greenhouse gases.
Greenhouse gases include
water vapor, carbon dioxide,
and methane.
The greenhouse effect is the
process by which these
gases form a blanket around
Earth trapping heat in the
atmosphere.
www2.uvawise.edu
The greenhouse effect is very important to life on
Earth.
Greenhouse gases in the
atmosphere make the Earth
warm enough to support
life.
Without it, temperatures on
Earth would climb during the
day and then drop below
freezing at night.
www2.uvawise.edu
According to some scientists
increased carbon
dioxide in the
atmosphere may
cause global
warming by
trapping more heat.
http://www.google.com/imgres?imgurl=http://1.bp.blogspot.com/-cEnNhEynsTs/TYfgtk0RC3I/AAAAAAAAAlc/0u-K4pd-3TE/s1600/Greenhouse-effect.jpg&imgrefurl=http://whereismyka.blogspot.com/2011/03/natures-wake-up-call.html&usg=__Qkja9mpUQAwHKumYyHsFnKu4H0=&h=324&w=550&sz=40&hl=en&start=0&zoom=1&tbnid=NmslNjY57rHK1M:&tbnh=110&tbnw=187&ei=9ymrTc2EFsP1gAfH5JGCCQ&prev=/images%3Fq%3Dgreenhouse%2Beffect%2Band%2Bglobal%2Bwarming%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1003%26bih%3D567%2
6tbm%3Disch0%2C201&um=1&itbs=1&iact=hc&vpx=463&vpy=189&dur=94&hovh=172&hovw=293&tx=155&ty=92&oei=9ymrTc2EFsP1gAfH5JGCCQ&page=1&ndsp=15&ved=1t:429,r:12,s:0&biw=1003&bih=567
FYI
Many of the heat –trapping
gases, such as carbon dioxide
have come from the increased
burning of fossil fuels.
In the past, Earth’s huge
forests have helped control
the greenhouse effect by
removing some of the carbon
dioxide from the air.
To slow down the overheating
of the planet some scientists
believe we need to decrease
the use of fossil fuels and
protect our forests.
theresilientearth.com
The Greenhouse Effect and Global Warming
Conduction, Convection and Radiation
http://www.youtube.com/watch?v=7Y3
mfAGVn1c
Heat refers to the energy transferred from a
hotter object to a cooler one.
Heat can travel from one place to another in three
ways:
Radiation p. 49
Conduction p. 50
Convection p. 50
• Both conduction and
convection require matter
to transfer heat.
3n1-combinescience.blogspot.com
Radiation is the direct transfer of energy by
electromagnetic waves.
Conduction is the transfer of energy by
direct contact (touching).
Convection is the transfer of heat energy
through liquids and gases by moving particles.
mit.whoi.edu
esrl.noaa.gov
Radiation, conduction, and convection in a lava lamp.
Radiation
The filament in the light bulb on a lava lamp
transfers energy by radiation and heats the glass
bottom of the lava lamp.
Conduction
The heated glass holding the “lava”, causes
molecules to speed up and spread out.
Convection
The warm “lava” rises because it is less dense.
The “lava” that is further from the energy source
cools causing molecules to move closer together.
The cooled “lava” sinks because it is more dense.
There is a relationship between the warming of
Earth’s atmosphere by the sun and convection
within the atmosphere and oceans.
http://www.propertiesofmatter.si.edu/images/L5/conv_cell_atmos_labeled.gif
serc.carleton.ed
Convection currents move warm air through the
atmosphere and warm water through the oceans.
http://www.propertiesofmatter.si.edu/images/L5/conv_cell_atmos_labeled.gif
serc.carleton.ed
The upward movement of warm air and the downward
movement of cool air form convection currents in the
atmosphere.
Air will rise if it is warmer
than the surrounding air.
Warm air will eventually
cool at higher elevations
and sink.
Convection currents in the atmosphere occur because cool air is
denser than warm air.
Cool, dense air sinks,
which forces the warm,
less dense air to rise.
Convection currents
cause most of the
heating of the
troposphere.
http://www.propertiesofmatter.si.edu/images/L5/conv_cell_atmos_labeled.gif
Cool air holds less water
vapor than warm air
because the particles are
closer together.
At a certain temperature
and pressure, water vapor
in a cooler air mass will
condense into liquid water
forming clouds and
possibly precipitation.
myweb.cwpost.liu.edu
Radiation, conduction, and convection work together to
heat the troposphere.
http://www.kudzuacres.com/wwow/lessons/weather/radiationconduction.gif
The warming of the Earth by the sun also
produces winds and ocean currents.
Convection currents move warm water through the oceans.
The warm water moves
above the cooler water, and
gives off its heat to the
surrounding environment.
As the water cools, it begins
to sink, warm water rises,
and the process begins
again.
Convection results in the
continual circulation of
ocean water on a global
scale.
Convection also plays a role in the movement of deep
ocean waters and contributes to ocean currents.
Like air, warmer water is less
dense and will rise above
cooler water.
Convection currents occur in
the ocean because cooler
waters sink and warmer
waters rise toward the surface.
The movement of water at
various temperatures helps
create ocean currents within
the water column.
chungpondemanisha.blogspot.com
An ocean current is the movement of ocean water and is
made up of warm or cool water.
An ocean current is caused by the uneven heating and
density of the ocean waters. (see p. 115)
Wind is the movement of air from areas of
high pressure to areas of low pressure.
http://www.weatherquestions.com/wind.jpg
FYI: Low Pressure Area (cyclone)
Winds are counter clockwise.
Warm air rises and spreads out
resulting in decreasing air pressure
and density.
The warm air and the water vapor
it holds cools and condenses.
The condensed water vapor forms
clouds resulting in storms and
precipitation.
FYI: High Pressure Area (anticyclone)
Winds are clockwise.
High-pressure centers contain
cool, dry air.
The high pressure and density is
due to the molecules being closer
together.
Cool air moves downward and
warms up.
Warm air is forced to rise and the
humidity drops.
Areas of high and low pressure are caused by
differences in the Earth’s temperature.
Differences in Earth’s
temperature are due to
the sun’s uneven
heating of the Earth’s
surface.
Winds develop as a
result of differences in
air temperature and air
pressure.
Unequal heating often occurs on land that is next to
a large body of water.
FYI:
Land heats up more quickly
than water.
The warmer air over the land
expands and rises, creating a
low pressure area.
Cooler air blows inland from
the water and moves
underneath the warmer air
creating a wind known as a
sea or lake breeze.
FYI:
At night land cools more quickly than water, so the air over the land
becomes cooler than the air over the water.
As the warmer air over the water rises, cooler air moves from the land
to take its place.
This flow of air from land to a body of water is called a land breeze.
Land and Sea Breeze Animation
http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?chapter_no=visualization
Local Winds
blow over short distances.
form when no winds are
blowing from farther away.
are caused by the unequal
heating of the Earth’s
surface within a small area.
Global Winds
are the movement of air
between the equator
and the poles caused by
the unequal heating of
the Earth’s surface.
blow from specific
directions over long
distances.
Since Earth rotates, global winds curve instead of
moving in a straight path.(The Coriolis Effect)
In the Northern Hemisphere
all global winds gradually
turn to the right.
In the Southern Hemisphere
all global winds gradually
turn to the left.
FYI: If Earth didn’t rotate,
global winds would blow in
a straight line from the
poles to the equator.
The Sun and Weather
FYI: Beaufort Wind Scale