Heat Tranfer Animations

Animation showing how heat circulates in convection

Conduction--Lightning can travel long distances in wires or other metal surfaces. Metal does not attract lightning, but it provides a path for the lightning to follow. Most indoor lightning casualties and some outdoor casualties are due to conduction. Whether inside or outside, anyone in contact with anything connected to metal wires, plumbing, or metal surfaces that extend outside is at risk. This includes anything that plugs into an electrical outlet, water faucets and showers, corded phones, and windows and doors.

 

Conduction in Non-Metals

Every atom is physically bonded to its neighbours in some way. If heat energy is supplied to one part of a solid, the atoms vibrate faster.

As they vibrate more, the bonds between atoms are shaken more. This passes vibrations on to the next atom, and so on:

 

Convection is energy transfer by movement of a material.  Heat causes material to become less dense – it then rises, cools, becomes denser and then sinks, only to repeat again.  In a pot of boiling water, the water gets heated at the bottom, rises to the top, cools when it hits the air, and then sinks again, forming a looped current. 

 

A graphic representation of the convection flow in such a simplified experiment is shown in the animation below.

A fluid layer heated from below and relatively cooled from the top (say, water kept in a vessel heated on a stove) is a simple free convection system, which experiences a local force imbalance in a gravitational field resulting in the convection of the fluid. This convection or displacement of some portion of the fluid (water, in our vessel) from one local position to another (inside the vessel) is the result of the buoyancy of the heated layer and the magnitude of it depends on the temperature difference prevailing between the top and bottom portion of the fluid layer (vessel)

 

Thermal Convection :

Energy from the sun heats the area. Let's say the soil region warms more rapidly than the adjacent water and grass surfaces. The soil in return radiates heat to the air directly above it. The warm air develops into a thermal, or warm parcel of rising air. The thermal then rises and moves off as another thermal develops. This process will continue as long as there is energy from the sun to heat the soil and the air.