Precipitation
Water from the atmosphere that falls to the ground as rain, snow, sleet, or hail.

Fuelwood
Branches, logs, and other tree parts that have been harvested or removed for use as fuel for cooking, heating, or producing power.

Radiant energy
Energy transmitted in the form of waves. Light, X-rays, and radio waves are all radiant energy.

Carbon source
A carbon pool that releases more carbon than it absorbs over some period of time. Examples include the burning of fossil fuels, forest fires, and livestock.

Geosphere
The solid land portion of the Earth as opposed to the atmosphere and the hydrosphere. Also called lithosphere.

Reasoning
Explanation that connects a claim to the evidence that supports it.

Claim
A concluding statement that answers a research question.

Glacier
A flowing body of ice, formed in a region where snowfall exceeds melting.

Respiration
A complex process that occurs in the cells of most living organisms, in which nutrient organic molecules such as glucose combine with oxygen and produce carbon dioxide, water, and energy.

Climate
The kind of weather a place has over a period of years, based on conditions of heat and cold, moisture and dryness, clearness and cloudiness, wind and calm.