The 15th means it's time for the 3rd of my 52 weekly Geo Challenges for 2017

Use a weather app such as Earth Null School, WindyTV and Ventusky to produce a piece of art by capturing a screenshot of an amazing or beautiful pattern.

You might also use a GIF maker to create an animated gif of your pattern.
I used the free GIPHY tool on Mac to make this one.

Please tweet or share with the hashtag #challenGEO3 so that I can collate them....