Seasons of Change
Science

The angle of incidence at which sunlight strikes the Earth
Angle of insolation
The angle of incidence at which sunlight strikes the Earth. angle of insolation. The angle of insolation refers to the angle at which sunlight hits the Earth's surface, affecting the intensity and distribution of solar energy.

A day in year when the Sun is directly over the equator, heading southward
Autumnal Equinox
A day in year when the Sun is directly over the equator, heading southward. Autumnal Equinox. It is the moment in fall when day and night are nearly the same length because the Sun is exactly above the equator.

All the wavelengths or frequencies of electromagnetic radiation
Electromagnetic spectrum
All the wavelengths or frequencies of electromagnetic radiation. Electromagnetic spectrum. The electromagnetic spectrum is the range of all types of light energy, from radio waves to gamma rays, that travel through space.