alternation

US /ˌɑːl.tɚˈneɪ.ʃən/
UK /ˌɑːl.tɚˈneɪ.ʃən/
1.

afwisseling

a situation in which one thing repeatedly happens or exists after another:

:
Flowers and trees are planted to produce an attractive alternation of light and shade in the garden.