How can Mars be warmed up?

Mars atmosphere gets cold and warm twice a day

Pasadena (USA) - The atmosphere on Mars is very thin and is only about one percent of the earth's air envelope. Nevertheless, it has surprising effects: it heats up and cools down every half day, scientists from the United States write in the "Geophysical Research Letters". Data from the Mars Reconnaissance Orbiter spacecraft show that temperatures in the central Martian atmosphere can move up and down by up to 32 degrees twice a day. The researchers suspect an explanation for the surprising find in the clouds of water ice in the Martian atmosphere.

"We see a temperature maximum in the middle of the day, but also one shortly after midnight," says Armin Kleinböhl from the Jet Propulsion Laboratory in Pasadena, California. The researchers used the Mars Climate Sounder instrument on board the spacecraft to study different regions on Mars at different times of the year. It has been known since the 1970s that temperature fluctuations on Mars can occur every half day. However, the researchers thought this was a peculiarity that should only occur during sandstorms on the Red Planet.

According to the new measurements, however, these variations occur throughout the year and across the planet. With the help of simulations, the researchers were able to show that water ice clouds at a height of ten to thirty kilometers are responsible for the effect. Although they are almost transparent to normal light, they absorb part of the thermal radiation that the warmed up Martian soil emits. They heat up in the process. Similar conditions occur on Earth, but only in the uppermost layers of the atmosphere. They cannot reproduce in the dense, lower atmosphere. The Martian atmosphere, on the other hand, is thin and water-rich enough. "We consider Mars to be a cold and arid world," says Kleinböhl, "but its atmosphere contains more water vapor than the upper layers of the earth's atmosphere."

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