Science U
Science U: Reasons for the Seasons
This webpage uses diagrams and video to explain the causes of the seasons.
Wikimedia
Wikipedia: Season
Encyclopedia entry for the seasons. Click on each specific season for more information.
Math Is Fun
Math Is Fun: A Day
How long is a day? What do most children do during certain hours of the day? What is day? This site offers the answers to these questions, lists the days of the week, and provides a hour-by-hour listing of what a typical kid's day...
Math Is Fun
Math Is Fun: The Seasons
Learn about the four seasons, when they occur in the northern and southern hemispheres, and why the seasons change as the Earth rotates around the Sun.
Other
Electric Sky: Vernal Equinox
This site, created by an amateur who has studied astronomy for thirty years, provides a scholarly explanation of the vernal equinox. Links to definitions of significant terms.