Convection
Heat can be transferred from one place to another by moving a fluid; this form of heat transfer is convection.
Newton's law of cooling:
We will encounter this same exponential function in a w-i-d-e variety of seemingly unconnected situations.
Tsurf is the temperature of the surface of the object. Tsrnd
is the temperature of the surroundings. 
T
is the difference in temperature between the initial temperature of
the object and its surroundings.
Examples:
Automobile cooling systems:
Heating and air conditioning systems:
These may be "active" with a forced blower,
Or they may be "passive", using only "natural convection" due to the change in density and bouyance of warm air,
Convection currents in a pan of water on a stove speed up the heating of the entire pan of water.
Convection currents are set up in the empty space inside a wall,
The main thing insulation does is to stop these convection currents,
Most of our ordinary weather is the result of convection:
 |
 |
||
|
|
|
||
|
|
|||