NASA Satellites Find Upper Atmosphere Cooling and Contracting Due to Climate Change
Since the mesosphere is much thinner than the part of the atmosphere we live in, the impacts of increasing greenhouse gases, such as carbon dioxide, differ from the warming we experience at the surface. One researcher compared where we live, the troposphere, to a thick quilt.
“Down near Earth’s surface, the atmosphere is thick,” said James Russell, a study co-author and atmospheric scientist at Hampton University in Virginia. “Carbon dioxide traps heat just like a quilt traps your body heat and keeps you warm.” In the lower atmosphere, there are plenty of molecules in close proximity, and they easily trap and transfer Earth’s heat between each other, maintaining that quilt-like warmth.
That means little of Earth’s heat makes it to the higher, thinner mesosphere. There, molecules are few and far between. Since carbon dioxide also efficiently emits heat, any heat captured by carbon dioxide sooner escapes to space than it finds another molecule to absorb it. As a result, an increase in greenhouses gases like carbon dioxide means more heat is lost to space — and the upper atmosphere cools. When air cools, it contracts, the same way a balloon shrinks if you put it in the freezer.
This cooling and contracting didn’t come as a surprise. For years, “models have been showing this effect,” said Brentha Thurairajah, a Virginia Tech atmospheric scientist who contributed to the study. “It would have been weirder if our analysis of the data didn’t show this.”
While previous studies have observed this cooling, none have used a data record of this length or shown the upper atmosphere contracting. The researchers say these new results boost their confidence in our ability to model the upper atmosphere’s complicated changes.
The team analyzed how temperature and pressure changed over 29 years, using all three data sets, which covered the summer skies of the North and South Poles.
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