The secret life of clouds…and other research

By learning more about the microscopic structure and physics of clouds, scientists are now better able to predict how the climate will respond. This research has been carried out as part of a major programme, funded by the Natural Environment Research Council (NERC), to determine what impact ice clouds have on the Earth’s climate system.

For the first time the scientists have shown that, within larger clouds, there are layers of super-cooled water cloud at temperatures as low as –30°C. These layers are not currently represented in weather and climate prediction models, but they are an important factor in determining whether the heat radiation is reflected back or allowed to pass through the cloud.

Research also shows that within the thin and wispy cirrus clouds that form from ice crystals high in the atmosphere, there are various concentrations of crystal numbers and shapes within different ‘regions’ of each cloud.

Programme leader, Professor Tom Choularton from the University of Manchester, explains why this is important. “The regions with small numbers of large crystals are relatively transparent and allow light through, whereas areas with an abundance of very small crystals scatter the incoming light. These differences have a huge effect on the amount of sunlight actually reaching the ground.”

A research team based at Imperial College, London, has developed a new instrument to measure the radiative properties of both ice clouds and clear air. They designed it for use on scientific aircraft and headed for Darwin in Northern Australia to observe the far infrared (very long wavelength) radiative properties of the skies around deep convective tropical storm regions.

Professor Choularton says,” This important work is still underway. We aim to link these measurements with the information we now know about the size, number and shape of ice crystals in clouds. The results will help us to test how well the effects of these clouds are represented in climate prediction and weather forecasting models.”

This research is just some of the exciting atmospheric science being showcased at a conference in London on Tuesday 23 January. ‘Our Changing Atmosphere’ highlights the work from four major research programmes to increase our understanding of the chemistry and physics of the atmosphere, and to quantify the effect of greenhouse gases on climate and air quality. NERC has invested £20 million in the four programmes.