Operation Cloud Lab

Confirmed for BBC Two on 23 July at 8.00pm to 9.00pm

Ep 2/2

Wednesday 23 July



Continuing their journey across the USA in the world’s largest airship, the Cloud Lab team encounter the dry western states before reaching the spectacular Pacific coast. Over the arid desert, the change in environment is immediately apparent - warm thermal air currents rising from its surface send the airship careering through the air.

Studying the relationship between life and the atmosphere, the team questions how the atmosphere changes with altitude - from close to the Earth’s surface to the edge of the jet stream - and how that impacts upon the life found there.

Microbiologist Dr Chris Van Tulleken and former paratrooper Andy Torbet search for living microorganisms in the ‘death zone’ of high-altitude. Andy undertakes a highly technical skydive, known as a ‘high altitude, high opening,’ or HAHO for short. Jumping from 26,000 feet, Andy has to overcome sub-freezing temperatures and fatally low levels of oxygen.

Their success in finding bacteria at altitude adds to other studies that demonstrate that life is far more robust than previously imagined. That in turn opens up all sorts of possibilities for the prospects for life in other extreme environments, beyond our planet.

Aboard the airship, expedition leader Felicity Aston and Dr Jim McQuaid explore the impact of human behaviour upon the atmosphere, questioning whether cities can create their own weather.

They unravel a mysterious increase in rainfall over the desert city of Phoenix, Arizona. A temperature survey of the city and the surrounding desert by both day and night reveals that the city generates thermals that force moist air upward where it cools and ultimately forms rain.

Dr Sarah Beynon enjoys her own close encounter with the Pacific wind and experiences first hand how animals use it. Taking to the air on a paraglider, she observes a trained Harris hawk as it circles her. It’s a unique opportunity to study up-close the adaptations that enable these birds to exploit updrafts and thermals to fly vast distances.