Cryosphere - This term refers collectively to the portions of the Earth where water is in solid form. This includes areas with snow cover, floating ice, glaciers, ice caps, ice sheets, along with areas of frozen ground. The area of the cryosphere shrinks during the summer season and then grows during the winter.

Cyclolysis - The process that occurs when a cyclone is weakening and decaying. At the end of cyclolysis, the cyclone has become extinct.

Smog - The first definition of smog was a mixture of smoke and fog in the atmosphere which reduces visibility. Over time smog has now changed its meaning to restricted visibility due to pollution emitted from human activities. A type of smog known as photochemical smog, common to heavily populated areas, forms when UV light from the sun reacts with low level pollutants such as nitrogen oxides. On hot days this reaction can create ozone gas at the surface which is dangerous to humans.

Tropopause - Zone of the atmosphere that marks the transition between the troposphere below and the stratosphere above. The tropopause is the top of the troposphere. 75 percent of the mass of the atmosphere is located below the tropopause. The height of the tropopause varies between 4 to 12 miles.

Evaporation or Mixing Fog - This type of fog forms when sufficient water vapor is added to the air by evaporation, and the moist air mixes with relatively drier air. The two common types are steam fog and frontal fog. Steam fog forms when cold air moves over warm water. This type of fog takes on the appearance of wisps of smoke rising off the surface of the water. The other type of evaporation fog is known as frontal fog. This type of fog forms when warm raindrops evaporate in a cool air mass near the ground.

Psychrometer - An instrument used to measure the water vapor content of the air. The first pantented instrument that was coined a "psychrometer" was invented in 1818 by a German inventor named Ernst Ferdinand August.

Deposition - The process where water turns directly from vapor to ice, without first becoming liquid. A common instance of deposition is when frost forms on the grass during cold mornings.