Describe this and that

What to describe there's no picture

This n that description

they are pronouns,n they are a part of grammer

This: used to identify a specific person or thing close at hand or being indicated or experienced.

That: used to identify a specific person or thing observed or heard by the speaker.

the sun's light combined with the visible wavelenghts form what is called ultraviolet radiation, which are the long waves at the end of a visible light sprectrum.

hope it ,

bioteacher101