Getting clouds right, especially in the new models that use smaller grid spacing to include clouds and storms, is important for calculating how much solar radiation reaches Earth. In February, which is summer in the Southern Ocean, about 90% of the skies are covered with clouds, and at least 25% of those clouds are affected by the type of ice formation that was the focus of the study. As these faster-growing, larger, ice shards fall (left side) less liquid water is left to spread out and disperse horizontally (right side). These shards grow as more water freezes to them, so shattering allows ice particles to grow in clouds at the expense of liquid drops. On the left, a large rimer, or ice chunk (blue sunburst) attracts liquid water, which freezes and then shatters to create shards (blue rectangles). Arrows at the top show that the cloud on the left reflects less sunlight (smaller arrow) than the cloud on the right, so more solar energy reaches the ocean’s surface. How ice behaves inside clouds affects the clouds’ 3-D shape and how much sunlight is reflected back to space. Doing so makes the clouds dimmer, or decreases their reflectance, allowing more sunlight to reach the ocean’s surface.

Results show that it’s important to include the process whereby icy particles collide with supercooled droplets of water causing them to freeze and then shatter, forming many more shards of ice. “Ice formation in Southern Ocean low clouds has a substantial effect on the cloud properties and needs to be accounted for in global models.” “Southern Ocean low clouds shouldn’t be treated as liquid clouds,” said lead author Rachel Atlas, a UW doctoral student in atmospheric sciences. The paper, published March 4 in the open-access journal AGU Advances, shows that including this ice-splintering process improves the ability of high-resolution global models to simulate clouds over the Southern Ocean – and thus the models’ ability to simulate Earth’s climate. New research led by the University of Washington shows that splintering of frozen liquid droplets to form ice shards inside Southern Ocean clouds dramatically affects the clouds’ ability to reflect sunlight back to space. National Center for Atmospheric ResearchĬlouds come in myriad shapes, sizes and types, which control their effects on climate. 29, 2018, during a field campaign involving the University of Washington that studied summer cloud cover around Antarctica. Clouds observed over the Southern Ocean on Jan.

Shards of Ice by R. Phoenix