It's already my 2nd postcard from Kazakhstan and I find it just as beautiful as the previous one :)
It shows the Aksu Dzhabagly, which is the "singing dune". In dry weather the sand makes a sound like an organ, which can be hears several kilometres away. The sands are over 3m high, stretch for over 3km and it has been standing on the same spot for 1000's of years.
I've never heard of singing dunes before :)