Heat flows from the heat source to cooler bodies. Heat is
transferred by three processes: Conduction, Convection, and Radiation.
When heat is conducted, it is led from the heat source by
travelling along a physical object.
Here two of Dr Viau's students are learning about conduction.
The young woman in the pink dress was using a straightened
out coat hanger wire to cook her marshmallow.
Metal is a good conductor of heat.
The heat from the fire travelled along the thick metal wire.
The wire got so hot that the student had to let go of it.
The young woman in the blue dress is using a wooden rod to
hold her marshmallow. Wood does not conduct heat well. The wood
in her hand is still cool and the marshmallows are almost done!
When heat is moved because something
warm is moving, then the heat is being transferred by convection.
Here you see convection happening over a fire. The hot air
This leaves empty space at the bottom of the column of rising
Cold air moves into the empty space and the fire warms it.
The newly warmed air also rises.
As the warm air gets close to the ceiling, it loses some heat.
Now this air is cooler. It follows the cool air which is falling.
The cool air falls and then is drawn upwards again.
Convection causes currents of warm and cool air to
Notice how convection is happening in this pan. The process
is the same in water and in air. It even happens in the hot magma
inside the earth.
Hot air, hot water, and hot rock all tend to rise.
lower. Cold air, cold water, and cool rock all tend to sink.
What happens in space?
Space is so empty that there is not much matter to warm up.
Heat travels by radiation.
Heat waves travel out into the void.
When they strike matter, they make the matter warmer.
The Sun's Radiation:
The sun emits many kinds of
radiation. Heat is only a part of what it emits.
The sun also emits light, radio
waves, gamma radiation, ultraviolet and infrared radiation.
All these forms of radiation
together are called the Solar Wind.
Header from NASA Earth From Space
1996,1997, 1998, 1999,
2000, 2002, 2003.
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