The weather on Mars is dusty — especially during the southern hemisphere’s spring and summer, when warmer temperatures produce stronger winds that stir the surface. Spinning columns of air known as dust devils are common, too, propelling dust much higher into the atmosphere, where it can stay suspended for days. The most extreme storms happen every few years and shroud the entire planet in a haze for months.
Why so dusty?
Scientists are still not sure what causes these global dust storms. In a recent study, however, researchers showed that Mars experiences a large energy imbalance at the same time major dust storms develop. The results reveal that the Red Planet absorbs up to 15 percent more solar energy than the thermal energy it emits back to space during southern spring, an excess of energy that continues into summer.
“Mars experiences intense variations in the amount of solar flux as it’s going around the Sun,” says lead author Ellen Creecy, an atmospheric scientist at the University of Houston.
This happens because Mars’ orbit is elliptical, meaning the planet is much closer to the Sun during southern spring and summer, when it receives more incoming solar radiation. But the researchers discovered that the power the sun emits doesn’t increase nearly as much. “The increase in emitted power can’t match the increase in solar flux,” says Liming Li, a planetary scientist at the University of Houston.