Oceans in the sky

By Jackson Dias

The storm clouds stretch menacingly across the sky. From the plane’s cockpit, towering, monstrous clouds are visible – enormous mushrooms, their tops white and luminous, rising from the ocean below. Overhead, at an altitude of 18,000 metres (57,000 feet) flies a U-2 aircraft – a former spy plane converted to serve as a cloud-watcher. At this altitude, it is beyond the reach of the mighty powers of the weather below. Six thousand metres lower, meteorologists in a Lear jet are violently shaken. Hail hammers their plane as it bounces, through swirling fog.

For six weeks in 1993, the two planes carrying members of an international team of researchers, flew through clouds above the central Pacific – in every sort of weather. The project, which also involved several ships and satellites, provided an in-depth look at the water cycle in the atmosphere, in which the clouds play a role. An even more ambitious co-operative study is planned for the skies above the Indian Ocean in 1998.

Meteorologists have long known that multiformed clouds have an indispensable function in our planet’s life. Indeed, they were the key regulators of global warmth. Clouds transport energy from the earth to the atmosphere and all around the globe, helping warm the earth and casting cool shadows.

Yet, their impact is extremely difficult to predict. Clouds are found in a space up to 20 kilometres (12 miles) high; they form with no warning and disappear almost as quickly. They exist in a vast variety of shapes and thicknesses. Predicting the movements of these emissaries of watery weather is equally difficult. To understand the workings of clouds, one must consider a long list of factors, which sometimes magnify each other’s effects and at other times, cancel each other out.

What is a cloud?

And yet, the origin of clouds is relatively simple: they form when warm, moist air encounters cool layers of air. This happens, for example, over mountains, but also when cold, heavy air masses force warmer, and therefore, lighter air up to higher altitudes, or when moist sea air encounters cold air masses over land.

Invisibly, the gaseous components of water molecules come together - they condense - and form clouds of vapour, not unlike the steam formed when boiling water comes out of a teapot and meets cooler air outside. But without the fine particles in the air would form even in air of 100 per cent humidity.

They bring rain and store warmth, their shadows cool the ocean. Changeable and unpredictable, clouds help provide global temperatures that allow life on earth to flourish. Researchers now say that clouds play a crucial role not just in global increasing climatic extremes, including catastrophic floods, horrendously violent storms and disastrous thoughts. The very future of the earth’s climate, scientists now say, is in the clouds.