I'm not sure specifically which 'man in stripes story' you're referring to. It could be about a man wearing striped clothes in a particular event, or perhaps it's a fictional story where the man in stripes has some unique role or adventure.
It depends on your perspective. Some might say it's realistic fiction because it explores common themes like self-acceptance and peer pressure, but others might argue it has fantastical aspects that make it less strictly realistic.
The stripes on the surface of the sand dune were formed by the wind. When the wind blew over the sand dunes, it would carry some sand away and form a depression on the leeward side of the sand dunes. At the same time, the wind would also pile up sand on the windward side of the sand dune, forming a bulge. The effect of this wind caused the surface of the sand dune to form stripe-like uneven patterns. The shape and direction of these stripes depended on the strength and direction of the wind, as well as the shape of the dune. Therefore, the stripes on the surface of the sand dune were the result of the interaction between the sand dune and the wind.
Since I don't know the exact 'man in stripes story', I can't say for sure who the main character is. It could be an ordinary man who just happened to be wearing stripes and got involved in an extraordinary situation.