Nighttime summer snows may be contributing to the snow on Mars's poles. [Image by NASA, ESA,The Hubble Heritage Team/STScI/AURA]
In the summer, snow falls in the Martian north every night. There have long been hints that there may be snow on Mars, but now we can be more certain.
Back in 2008, the Phoenix lander spotted some snowflakes falling gently to the Martian ground. Simulations have also shown that in the past, when Mars had more water than it did now, it may have had its share of snowstorms. However, according to the data from the Mars Global Surveyor and the Mars Reconnaissance Orbiter spacecraft, snowstorms still occur nightly on Mars in the summertime.
The simulations may be virtual, but that as well as the data from the Phoenix lander all tie in nicely. However, the snowstorms on Mars aren't the same as the snowstorms on Earth. If and when humans finally set foot on Mars, a blizzard won't be something they would have to contend with—not anytime soon, anyway.
What virga rainfall looks like on Earth [Photo by Susan Jensen]
According to a recent study, Mars's summertime snows occur in bursts that can last for several hours. The laser-based observations of the Phoenix lander shows that what Mars experiences is actually a “virga” snowfall. In a virga snowfall, snow forms high up in the atmosphere, but some of the snowflakes turn from solid to gas before they hit the ground. Thus, in the morning, there's only a light dusting of snow on the ground—just a hint of the snowstorm that occurred just the night before. The robots on Mars are also unable to directly observe the snowstorms, which could be happening high in the sky just above them.
Aymeric Spiga, one of the authors of the study, says that the snowstorms can be quite violent. However, there won't be much evidence of the snowstorms on the ground when they pass. There's going to be a bit of snow on Mars and its surface, but, as Spiga says, “[t]here’s not enough to build a snowman.”
Still, this doesn't discount the significance of the storms. The snows are still likely to be an important part of the water cycle on Mars. After all, the snows probably have some sort of impact on the planet's water distribution.
Snow on Mars's pole [Image by Cindy Starr/NASA]
What, however, are these simulations we keep mentioning? Spiga and his team created a high-resolution computer model that showed what's occurring in the Martian atmosphere. The water-ice clouds emit an infrared light that lowers the temperature in the atmosphere around them. As a result, blotches of freezing air form and settle over warmer air. The cold air then sinks, subsequently causing unexpectedly violent winds. Convective currents then push snow particles to the ground.
If scientists can accurately understand the present climate patterns on Mars, they can also get a better idea of what water was like on the planet in the past. Further Mars climate simulations can also contribute to existing global models that scientists use to study Mars.
Just a decade ago, scientists were a little dismissive of the snow on Mars. With further study and advancements in technology however, we now see that these snows play a more important role than previously thought.
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