What Are Clouds Made Of?

May 01, 2017

What are clouds made of? It turns out the water that makes up clouds (liquid, ice, or a mixture of both) can have a big impact on climate, according to a new study published by the Journal of Geophysical Research. Led by Alex Matus, the study presents a recent update to a satellite dataset that could make future climate predictions more accurate. The dataset, called 2B-FLXHR-LIDAR, combines measurements from a suite of A-Train sensors (CloudSat/CALIPSO/MODIS) to estimate global energy flows in the atmosphere. These measurements give a rare glimpse into the internal structure of clouds to reveal cloud phase, a critical missing piece of the climate puzzle.

Our understanding of cloud phase is cloudy, but better estimates are on the horizon. Matus and L'Ecuyer used the updated dataset to determine the influence of different cloud phases on solar and terrestrial radiation. For the first time, the study found that clouds consisting entirely of liquid or ice account for nearly half of the net cooling effect of clouds on climate. Interestingly, mixed-phase clouds consisting of a mixture of liquid and ice are found to contribute about a third of the net cooling effect, particularly at higher latitudes, with the remaining contribution from multi-layered cloud systems. By shining new light on a cloudy problem, this study highlights the importance of accurately simulating cloud phase in climate predictions.

An article in EOS detailing this work can be found here.