Wednesday, August 15, 2012

Weather Whys Wednesday: Weather on Mars

With all the attention in recent days focused on the successful (and pretty awesome) landing of Curiosity on Mars, I figured we might as well talk a little bit about what we know about the weather on Mars.

View from Mars Curiosity looking toward Mt. Sharp.
Credit: NASA/JPL-Caltech/MSSS
Mars has a very thin atmosphere. It's stated to be less than 1% of the atmosphere on Earth. Earth's atmosphere is 78% Nitrogen, just about 21% Oxygen, and roughly 1% Argon. Carbon Dioxide is about 0.04% of our atmosphere. The rest is trace gases. On Mars, CO2 makes up 95% of the atmosphere! Nitrogen follows at 3% and Argon checks in at just over 1.5%. Despite all the CO2 in the Martian atmosphere, it "only" really adds about 40 degrees of warming to the planet, so while the greenhouse effect is at can only help so much.

Speaking of temps, observations of temperature on Mars have been reported to range from as warm as +1F to as low as -161F, via observed data. It's estimated that temperatures can range from as high as 80 degrees all the way down to -220 degrees. What's more impressive is that since Mars doesn't really hold on to heat very well, the diurnal range in temperature there is incredible, and can fluctuate 100 degrees or more in a given day between nighttime low and daytime high.

The barometric pressure here on Earth averages around 1015 mb, give or take. We know that the strongest hurricanes can have the barometer drop to 900 mb or less and wintertime high pressure can be as strong as 1060 mb or higher. On Mars, the average pressure is a total of 6 mb.

Mars has no magnetosphere, which may be one reason why Mars has such an insubstantial atmosphere. Solar winds are not deflected around Mars as they are Earth, which means that they can interact with the Martian atmosphere, specifically the ionosphere of Mars. So ions will form at the top of the ionosphere, but they'll get stripped away because of these interactions, preventing the Martian atmosphere from expanding. Despite all this, Mars has processes that allow for breezes to develop. With all the dirt and soil on the planet, Mars is noteworthy for massive dust storms. With dust being blown about on the planet, it allows for the sky to take on the red hue Mars has become known for.

So we have some idea of how Mars works, but we lack a lot of good observations. Thankfully, Curiosity will allow for an awful lot of new data to be collected to better understand Mars, including observations every five minutes for the next two years. Additionally, NASA is planning the "Mars Atmosphere and Volatile EvolutioN" mission later next year. The goal is to better understand how Mars lost so much of its atmosphere over time. Over the next 5-10 years, we should learn an awful lot about the Martian atmosphere, historical climatology, and daily weather, which should hopefully allow us to better understand if life was or is possible on the Red Planet.

Some references for you...

Universe Today article on the atmosphere of Mars answers on the Martian atmosphere

Georgia State Physics/Astronomy Department info on Mars

Wiki article on the Climate of Mars