US Geological Survey
U.s. Geological Survey: Water Cycle
An in-depth explanation of the Earth's water cycle, including a hyperlinked diagram that provides direct access to information about each phase in the cycle.
Ohio State University
Osu: Beyond Weather and the Water Cycle: The Sun: Earth's Primary Energy Source
Extensive article that discusses the first principle of climate science, i.e., that the Sun is the primary energy source for the climate system of the Earth. Presents five concepts for this principle and explains each, providing...