Glossary
Earth's tilt
The inclination of Earth's rotational axis at approximately 23.5 degrees relative to its orbital plane around the sun. This tilt is the primary cause of Earth's seasons.
Example:
Without Earth's tilt, every location on the planet would experience roughly the same day length and temperature year-round, eliminating distinct seasons.
Equator
The imaginary line around the middle of the Earth, equidistant from the North and South Poles, located at 0° latitude. It receives the most direct solar radiation year-round.
Example:
Tropical rainforests thrive near the equator due to consistent high temperatures and abundant rainfall, driven by direct sunlight.
Equinoxes
Two points in Earth's orbit (spring/vernal and fall/autumn) when the Earth's axis is neither tilted toward nor away from the sun. This results in approximately equal lengths of day and night across the globe.
Example:
During the autumnal equinox, many deciduous trees begin to change color as the balance of day and night signals the approach of colder weather.
Higher Latitudes
Geographic areas located further away from the equator, towards the Earth's poles. These regions receive solar radiation at a more angled incidence.
Example:
Polar bears are adapted to the cold climates found at higher latitudes, where sunlight is spread over a larger area, leading to less intense heating.
Latitude
A geographic coordinate that specifies the north-south position of a point on Earth's surface, measured in degrees from the equator.
Example:
Regions at higher latitude experience more pronounced seasonal changes in temperature and day length.
Solar radiation
The electromagnetic energy emitted by the sun that travels through space and reaches Earth. It is the primary energy source for Earth's climate and ecosystems.
Example:
The intensity of solar radiation reaching a desert biome contributes to its extreme temperatures and arid conditions.
Solstices
Two points in Earth's orbit (summer and winter) when the Earth's tilt is most directly toward or away from the sun. These mark the longest and shortest days of the year, respectively.
Example:
Ancient civilizations often built monuments aligned with the solstices to track the sun's extreme positions and mark the changing seasons.
Summer solstice
The day in a hemisphere when the Earth's axis is tilted most directly towards the sun, resulting in the longest period of daylight for that hemisphere.
Example:
In the Northern Hemisphere, the summer solstice is often celebrated as the longest day, providing extended hours for outdoor activities.
Winter solstice
The day in a hemisphere when the Earth's axis is tilted most directly away from the sun, resulting in the shortest period of daylight for that hemisphere.
Example:
The winter solstice often brings the coldest temperatures as the hemisphere receives the least direct sunlight and experiences the longest night.