Shortwave radiation occurs from the sun which is known as K*. Longwave radiation is known as L* and can occur from clouds etc.

The relationship between the shortwave radiation and the time of the day is that both depend with the latitude.

Ultraviolet radiation and shorter waves are consider "shortwave radiation" they begin at about 300 to 350 nm (just past violet in the visible spectrum)

Yes it is.

Visible light or Shortwave are radiation and it contain energy, when these radiation hit earth surface some fraction of radiation is absorb and transform from radiation energy to thermal energy.

"shortwave", centered in the visible