4.7 Solar Radiation & Earth’s Seasons

Insolation

The amount of solar radiation (energy from the sun's rays) reaching an area, measured in Watts/m².

Solar Intensity

The intensity of incoming solar radiation, which depends on the angle of the sun's rays and the amount of atmosphere the rays pass through.

Equinox

A point in the year when day and night are approximately equal in length, occurring in March and September.

Solstice

The time during the year when one hemisphere is maximally tilted toward the sun (June for Northern Hemisphere summer, December for Northern Hemisphere winter).

Albedo

The proportion of light that is reflected by a surface; high albedo surfaces reflect more light and absorb less heat.

Urban Heat Island

An urban area that is significantly warmer than its surrounding rural areas due to human activities and low albedo surfaces.

Tilt of Earth's Axis

The angle of Earth's rotation which causes the changing seasons and variations in daylight hours.

Solar Noon

The time of day when the sun is at its highest point in the sky, resulting in the shortest shadow.

Shadow Length Variation

The length and position of shadows change with the time of year and the time of day due to the sun's position.

Solar Radiation Variation

The amount of solar radiation received at a location is highest during the longest summer day and lowest during the shortest winter day.