Transcript Convection - Mr. Wieners 8th Grade Science

The TEKS
Know that climatic interactions exist among
Earth, ocean, and weather systems.
• 8.10 (A) recognize that the Sun provides the
energy that drives convection within the
atmosphere and oceans, producing winds and
ocean currents;
CONVECTION
Transfer of heat by the movement of
warmed fluid (air or liquid)
Warm fluid rises (less dense)
Cool fluid sinks (more dense)
CONVECTION
CONVECTION
CONVECTION
Moves air in the atmosphere!
Moving Air = Winds
Convection in the atmosphere
is the main cause of the wind.
Where does the Energy for
Convection come from on
Earth?
THE SUN!!!
CONVECTION
CONVECTION
causes deep ocean currents!
CONVECTION
Wind over the
shore changes
direction
because of
EARTH’S
UNEVEN
WARMING &
COOLING!
Hot Air is Less Dense!
Atmospheric Density
How high is the atmosphere?
99% is within 30 km / 18
miles of the surface of the
Earth
Half the atmosphere is 5 km /
3.5 miles above the surface of
the Earth
Air Pressure – the weight of the air pressing on the
surface at a give location
What is most
dense
SINKS!
Atmospheric Movement
MOSTLY CAUSED BY:
- Temperature differences
- Pressure differences
- Coriolis Effect (due to Earth’s rotation)
Air Movement
Gas molecules move from high density to lower density
The TEKS
Know that climatic interactions exist among
Earth, ocean, and weather systems.
• 8.10 (B) identify how global patterns of
atmospheric movement influence local
weather using weather maps that show high and
low pressures and fronts;
We would
expect…
Coriolis Effect breaks up
Global Circulation
• On Earth the large
circulation cell breaks up
into 3 smaller ones,
moving diagonally
• Other worlds have more
or fewer circulation cells
depending on their
rotation rate
The Coriolis effect
• The Coriolis effect
– Is a result of Earth’s rotation
– Causes moving objects to follow curved paths:
• In Northern Hemisphere, curvature is to right
• In Southern Hemisphere, curvature is to left
– Changes with latitude:
• No Coriolis effect at Equator
• Maximum Coriolis effect at poles
The Coriolis effect on Earth
• As Earth rotates,
different latitudes
travel at different
speeds
• The change in speed
with latitude causes
the Coriolis effect
Figure 6-9a
Global Winds - winds that blow steadily
in paths for thousands of kilometers
Total Atmosphere Circulation
Role of the Ocean
• Slowly absorbs and slowly releases heat
energy helping keep Earth’s temperatures
relatively stable
• Oceans heat or cool the air above them and
transport heat around the globe in currents.
• Hurricanes form over warm ocean water,
drawing their energy from the water’s heat.
Ocean Currents
Currents
•
large scale water movements
– occur everywhere in ocean
– both surface and deep
•
2 main types: surface currents (10%) and subsurface currents (90%)
– surface currents are primarily wind driven
– deep currents are density driven
– other forces affecting currents
Coriolis effect
friction
gravity
thermal expansion
geologic shape of ocean basin
Major oceanic circulation systems
Current Gyres
Gyres are large circular-moving loops of water
Five main gyres (one in each ocean
basin):
• North Pacific
• South Pacific
• North Atlantic
• South Atlantic
• Indian
• Generally 4 currents in each gyre
• Centered about 30o north or south
latitude
Wind-driven surface currents
Lost at Sea
Duckie Progress
•January 1992 - shipwrecked in the Pacific Ocean, off the coast of
China
•November 1992 - half had drifted north to the Bering Sea and
Alaska; the other half went south to Indonesia and Australia
•1995 to 2000 - spent five years in the Arctic ice floes, slowly
working their way through the glaciers
•2001 - the duckies bobbed over the place where the Titanic had
sunk
•2003 - they were predicted to begin washing up onshore in New
England, but only one was spotted in Maine
•2007 - a couple duckies and frogs were found on the beaches of
Scotland and southwest England.
Other Effects of Wind on Water Movement
a) Downwelling – results when two wind-driven surface currents collide
OR when a wind-driven surface current collides with a land mass
two surface currents colliding
surface current colliding with land mass
b) Upwelling - results when two wind-driven surface currents move away
from each other OR when a wind-driven surface current moves away
from a land mass
two surface currents pushed in opposite directions
surface current pushed away from land mass
Surface and Deep-Sea Current
Interactions
Unifying concept: “Global Ocean Conveyor Belt”
http://seis.natsci.csulb.edu/rbehl/ConvBelt.htm
The Water Cycle
Four Types of Fronts
Cold Fronts
A cold front forms when cold air moves underneath warm air,
forcing the warm air to rise.
Cold
Front
On Weather
Map
How can you tell
which direction the
front it moving from
the map?
Four Types of Fronts
Warm Fronts
- A warm front forms when warm air moves over cold air.
What kind of weather forms at a warm front?
Warm
Front
On Weather
Map
How can you tell
which direction the
front it moving from
the map?
Stationary
Fronts
Where the warm and cool air
meet, water vapor in the warm
air condenses into rain, snow,
fog, or clouds.
Occluded Fronts
When a cold air mass and a
cool air mass come together,
the warm air caught between
them is forced upward.
Reading Weather Maps
http://0.tqn.com/d/weather/1/0/B/-/-/-/weathersymbolssummary.jpg
Read the Legend!!!
Radar
http://www.crh.noaa.gov/arx/?n=jul2409
Local Weather….
http://www.wunderground.com/maps/#?type=Fronts
The TEKS
Know that climatic interactions exist
among Earth, ocean, and weather
systems.
• 8.10 (C) identify the role of the oceans in the
formation of weather systems such as
hurricanes.
http://www.weatherwizkids.com/weather-hurricane.htm
What Happens On Land?
• Landfall
After a few hours over land, a hurricane will
weaken rapidly. WHY?
• Without the moisture and heat sources
provided by the ocean, the storm can no
longer produce thunderstorms near the eye.
Without this convection, the storm's energy
dissipates.
Recommended Resources…
• Edheads – Reading a Weather Map Tutorial & Interactive Game
• http://edheads.org/activities/weather/index.shtml
• Current Weather Maps – (different maps for temp, pressure,
moisture, etc)
• http://weather.rap.ucar.edu/surface/
• Weather - Easy Interactive Barometer
• http://kids.earth.nasa.gov/archive/air_pressure/barometer.html
• Air Force Association that Flies Into Hurricanes to Collect Data!
• http://www.hurricanehunters.com/
• Short video clip about their mission
http://oceantoday.noaa.gov/hurricanehunters/welcome.html
• NOAA – Education Resources
• http://www.education.noaa.gov/
• Bill Nye – Storms
• http://www.gamequarium.org/cgi-bin/search/linfo.cgi?id=7827
Other Files You Might Like…
•
•
•
•
Edusmart
BrainPop – Weather
Unit Organizer
Bill Nye – Storms – check out the clearest, most
fun explanation of El Nino ever!! (also has
Winds, Atmosphere,etc)
• Evaporation & Condensation Lab
• STEMscopes
• Texas STAAR Coach