Music that describes nature tells a story is known as

Program music

Explanation:

Program music is the type of music characterized by being a kind of narrative music, or music that describes nature. It is a song composed to “tell a story”, with descriptive characteristic, that intends to evoke images in the listener's mind. During romanticism, a great deal of programmatic work emerged, especially for piano. But it was in the orchestral works that this kind of music has gained its fame to this day. It was with the help of the orchestra that the composers were able to express the descriptive potential with greater skill.

i think descriptive but i'm not 100% sure.. sorry.