They are designed to be inherently stable in flight; if disturbed by a gust of wind or a thermal current they will return automatically to stable flight.

On its arrival this atmospheric weakness allowed thunderstorms to barge high into the sky as daytime heat forced thermal currents upwards.

Its wide valley sides are perfect for generating the thermal currents needed for great hot-air ballooning.

But close to the oil installations, the only signs of wildlife are the vultures circling on thermal currents above flare stacks burning off unwanted gas and emitting an acrid smell.