The biosphere is the global ecological system integrating all living beings and their relationships. This includes their interactions with the lithosphere (the rigid outer part of the earth, consisting of the crust and upper mantle), hydrosphere (all surface water), and atmosphere (the envelope of gases surrounding the planet).

More familiar in the United States is the Fahrenheit scale in which the freezing point of water is 32°F (0°C) and the boiling point is 212°F (100°C). To convert from C° to F° use the formula:

\(F° = {9 \over 5}C° + 32\)

and to convert from F° to C° use:

\(C° = {5 \over 9} (F° - 32)\)

An air mass is a large body of air that has similar moisture (density) and temperature characteristics. A front is a transition zone between two air masses.

Rising into the atmosphere, the water condenses into clouds. When the clouds become too saturated with water, the water is released as snow or ice precipitation which may warm as it falls to reach Earth as rain.

Part of the peripheral nervous system, the somatic nervous system is made up of nerve fibers that send sensory information to the central nervous system and control voluntary actions.