1. Introduction to Thermal Physics
What is Temperature?
•The degree of hotness or coldness of a body or environment.
•A measure of the warmth or coldness of an object or substance with reference to some standard value.
•A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale.
•A measure of the ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system.
•Any of various standardized numerical measures of this ability, such as the Kelvin, Fahrenheit, and Celsius scale.
How a Thermometer Works
As the temperature of the liquid in a thermometer increases, its volume increases.
The increase in volume is thus due to a change in height of the liquid within the column.

2. Celsius  water freezes at 0 and boils at 100 degrees
Temperature Scales
Kelvin temperature scale, which is the standard metric system
The zero point on the Kelvin scale is known as absolute zero.
Celsius  water freezes at 0 and boils at 100 degrees
Fahrenheit  water freezes at 32 and boils at 212 degrees
Kelvin  zero is absolute zero (-273 degrees C)

3. What is Heat?
Heat is simply the transfer of energy from a hot object to a colder object.
Thermal Equilibrium

4. Methods of Heat Transfer
Conduction – heat transferred between materials in direct contact
Conductors – materials that transfer heat energy well
- elements with loosest outer electrons are best
- silver, copper best followed by aluminum then iron
Insulators – materials which delay the transfer of heat energy compounds with trapped air spaces
- liquids and gases
Convection – heating that occurs through currents in a liquid or a gas
used to heat and cool homes and buildings provides the engine which produces wind
Radiation – heat transmitted through electromagnetic waves radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays longest shortest wavelengths Lower temperatures emit longer waves Higher temperatures emit shorter waves

6. Transmission of Heat
Radiant Energy – any energy transmitted by electromagnetic waves (radiation)
 As an object gets hotter, some of its radiant energy is given off as visible light
Absorption – opposite of reflection  good absorbers reflect very little radiant energy  good reflectors are poor absorbers  good absorbers are good emitters

7. The Greenhouse Effect
Terrestrial Radiation – long wave radiation emitted by earth into outer space
Solar Radiation – short wave radiation emitted by the sun
The greenhouse effect is a result of the atmosphere’s inability to release our terrestrial radiation