Operation Cloud Lab: Secrets of the Skies

Flying coast to coast across the United States aboard one of the world's largest airships, a team of scientists undertake a series of exciting experiments shedding light on the causes of wild weather, how life exploits the atmosphere, and the human impact upon the weather. The team begins their voyage with an exploration of clouds. Expedition leader and meteorologist Felicity Aston examines how clouds capture liquid water and tries to weigh a cloud in an ambitious experiment. Andy Torbet, former paratrooper, sets out to measure the forces that keeps clouds afloat by parachuting through the turbulent and hazardous air that surrounds a large cumulus cloud. Microbiologist Dr Chris Van Tulleken examines one of the most radical theories in meteorology today - that some clouds are actually alive, and as a consequence are more likely to form rain than others. Finally, the team examine why there has been an increase in hurricanes along the Gulf Coast in recent years. Their investigation leads to some suprising results.

Continuing their journey across the USA in one of the world's largest airships, the team questions how the atmosphere changes with altitude and how that has an impact on 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. Parachuting from 26,000 ft, Andy has to overcome sub-freezing temperatures and fatally low levels of oxygen to undertake the experiment. 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. Dr Sarah Beynon paraglides for a close encounter with a hawk and a unique opportunity to study up-close the adaptations that enable these birds to fly so effortlessly. To conclude their expedition the team scuba dive in the giant kelp forest of Monterey Bay, California, to discover how the atmosphere creates habitats below the ocean surface. One of the most fertile and diverse habitats in the seas, it is a vivid demonstration of the power of the atmosphere to reach in to every corner of the planet, and make it a place for life.