word request - What are these flying things called in English?

I saw something flying today. What should I call it in English?

Answer

bytebuster has the provided the correct term, although I would parenthesize it like this: (hot air) balloon. That is, these objects can simply be called balloons, or hot-air balloons if you want to be more specific.

Also, it may be worth noting that many dictionaries hyphenate the descriptive hot-air, although that hyphen is regularly omitted in the literature.

Hot air balloons belong to the family of flying machines called aerostats, or lighter-than-air flying aircraft. However, it should be noted that I've added that hypernym simply for reference purposes; the word aerostat is a more technical term that's seldom heard in day-to-day speech. In conversation, I'd expect to hear something more like:

Blimps and hot-air balloons are lighter-than-air aircraft.