Sunlight amounts to about one kilowatt of heat per square meter of the earth's surface. A Calorie is 1000 calories, and should always be called a kilocalorie, but it is common practice in food labeling and nutritional references to simply call it a Calorie. The food Calorie is the kilocalorie. A calorie is the quantity of heat required to raise the temperature of one gram of water, one Celsius degree. A Calorie or kilocalorie is the amount of heat required to raise the temperature of one kilogram of water one Celsius degree.
Temperature is a measure of the concentration of heat, or the average amount of motion per molecule.
Molecules in rapid motion have a higher temperature than those that are moving more slowly. Adding heat to a substance makes the molecules move faster, and therefore increases the temperature. There is an exception to this, however. At a certain temperature, specific to each kind of matter, additional heat will change the substance from a solid to a liquid, or from a liquid to a gas, without any increase in temperature. In the case of water, adding heat to ice at 0 degrees Celsius produces water at 0 degrees Celsius.