What Rains on Mars?

It doesn’t rain on Mars, at least not as we know it on Earth. Instead, what falls from the Martian skies is often snow, or more precisely CO2 snow at the poles, and dust. In the absence of liquid water and considering the extreme cold, the Martian atmosphere experiences unique weather phenomena that are quite different from anything on our planet.

Dust: The Martian Air's Natural Ingredient

Dust reigns supreme in the Martian weather. Not only do dust storms frequently occur, but the dust itself can also precipitate from the clouds. However, it’s important to note that the dust falling from the Martian sky is not like the water-based rain or snow we experience on Earth.

Water Ice and Carbon Dioxide Ice

Unlike Earth, where clouds and precipitation are driven by vast amounts of water vapor, Mars has only small amounts of water ice and CO2 ice clouds. These Martian clouds can occasionally produce snow made of these two ice types. Even though water ice can form, it’s more commonly CO2 (dry ice) snow that falls from the clouds, especially in the polar regions.

Static Discharges in Martian Dust Storms

Another fascinating aspect of Martian weather is the phenomenon of dust devils. These are relatively small but intense whirlwinds of dust that are significantly larger on Mars than on Earth. Due to the low density of the Martian atmosphere, these dust devils can be seen emitting a faint glow as they generate static discharge, making them look like mini-gauges glowing in the Martian night. On Earth, similar phenomena can be observed in places like White Sands National Monument, where blowing gypsum dust forms static discharges visible to the human eye.

Wave of Unicorns and Fairy Dust

Even with all its unique weather patterns, the Martian atmosphere doesn’t exactly feel like the setting for a fairy tale. However, it does conjure up the image of fairies and unicorns playing leapfrog, perhaps dancing in the dust devils. The dusty, dry environment is a stark contrast to the lush, stormy landscapes we’re more familiar with. While the science behind Martian weather is fascinating, it also leaves room for imagination and wonder.

A Great Movie, Minor Technical Inaccuracies

One of the few instances of Martian weather depicted accurately in cinema is the perfect storm of dust and dust devils in ldquo;The Martian.rdquo; Though the movie is highly acclaimed, there’s one minor technical inaccuracy: the dust storms on Mars are described as being equivalent to hurricane-force winds. While the wind speeds can indeed be fierce, the effect on the ground is more like a strong breeze due to the low density of the atmosphere. On Earth, a 100 mi/hr wind would lift sand and small rocks, but on Mars, it’s more akin to fine talcum powder, creating a much gentler breeze.

Exploring the unique weather phenomena of Mars not only provides insights into the planet’s atmospheric conditions but also sparks the imagination. Whether it’s the static discharges in dust devils or the CO2 snow, Mars continues to captivate our curiosity and inspire scientists and enthusiasts alike.