Atmospheric pressure: Pressure caused by the weight of air above the surface of the earth.

Barometer: A device for measuring atmospheric pressure or changes in atmospheric pressure.

Altimeter: A device that measure the altitude (above sea level) usually a modified barometer.

Aneroid barometer: A barometer that consists of a sealed corrugated metal container that changes its shape slightly as the atmospheric pressure changes.

Buoyancy: The lifting force caused by the difference in density between an object and the fluid surrounding (or below) the object.

Bernoulli’s principle: As the velocity of a fluid increases, the pressure exerted by that fluid decreases.

Conduction: The flow of heat by conduction occurs via collisions between atoms and molecules in the substance and the subsequent transfer of kinetic energy.

Convection: Convection is the flow of heat through movement of matter (in fluids) from a hot region to a cool region. Natural convection occurs when buoyant forces cause warmer, less dense, material to move away from the source of heat and mix with more dense, cooler, material.

Coefficient of linear expansion: A measure of the amount by which a solid will increase in length as a result of a 1º increase in temperature.

Coefficient of volume expansion: A measure of the amount by which the volume of a material will increase as a result of a 1º increase in temperature.

Equilibrium: A state of balance – when movement or change in one direction equals the movement or change in the opposite direction.

Fusion: Melting. Conversion from solid to liquid.

Heat: Energy in motion. Heat occurs when energy is transferred from one point to another under the influence of a temperature difference.

Latent Heat: Energy change without change in temperature.

Latent Heat of Fusion: Energy needed to convert solid to liquid without increasing the temperature.

Latent Heat of Vaporization: Energy needed to convert liquid to vapor without increasing the temperature.

Radiation (thermal): Electromagnetic radiation emitted from a heat or light source as a consequence of its temperature - primarily ultraviolet, visible, and infrared radiation.

Specific Heat Capacity: The amount of energy needed to increase the temperature unit mass of a substance by 1 degree.

Temperature: The temperature of a body of matter is a measure of the kinetic energy of the motion of its particles.

Thermal equilibrium: Two or more objects are in thermal equilibrium when there is no net exchange of energy between them. This occurs when the temperatures of the objects are the same.

Thermal conductivity: A measure of a material’s ability to conduct thermal energy. Thermal conductivity is the quantity of heat transmitted per m² per second as a result of a temperature difference of 1ºC.