A disturbance propagating through a continuous medium. It gives rise to a periodic motion. A wave transports energy and information but not matter. A wave is characterized by its amplitude, the wavelength or wave number, the wave period or (angular) frequency, and the phase.

The average time interval between passages of successive crests (or troughs) of waves.

The distance between successive crests or troughs in a wave.

It is the result of non-linear interaction of gravity waves.

It is a small and very dense star composed mostly of electron-degenerate matter. Your mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored thermal energy.

The rate at which wind velocity changes from point to point in a given direction (as, vertically). The shear can be speed shear (where speed changes between the two points, but not direction), direction shear (where direction changes between the two points, but not speed) or a combination of the two.

At mid latitudes, F2 frequencies are lower in Summer than in Winter, despite the smaller solar zenith angle during Summer. This phenomenon occurs mostly around solar maximum.

It is a a quantity which measures the number of sunspot and groups of sunspots present on the surface of the Sun.