Alan McStravick for redOrbit.com – Your Universe Online
With all the attention being paid to Mars, we are learning something new about the red planet almost daily. Each new revelation is pretty heady information. But what about the weather on our celestial neighbor? One of the most common questions that people have is whether Mars is hot or cold.
The early days of Earth was marked by a climate that was both warm and wet, and mirrors what Mars was like some 3.5 billion years ago. However, with the atmosphere on Mars consisting primarily of carbon dioxide and water, a series of chemical reactions occurred at some point in the distant past that caused the formation of carbonate rock. The smaller size of Mars and its lack of a tectonic system precluded the recycling of the rock back into carbon dioxide. For this reason, the atmosphere of Mars has become exceptionally thin.
So is Mars hot or cold? A thin atmosphere means that the temperatures tend to be very cold. Any water that might remain on Mars is therefore frozen in the Martian poles as permafrost or hidden deep underground in a spring system.
Depending on just where on the red planet you might be, the temperature can vary greatly. While the summer temperatures at the equator can reach as high as 70 degrees Fahrenheit at noon, the temperature at the poles can drop to -225 degrees Fahrenheit. These wild swings in surface temperature make the planet an inhospitable environment for human life. It also poses significant challenges for the electronics and mechanical parts of any machinery that scientists send to the planet.
Humidity, which is a measure of the water vapor present in the air, is another area in which Martian weather can be extremely volatile. In the cold night hours, the humidity on Mars can be as high as 100 percent. During daylight hours, however, the air becomes undersaturated as a direct result of the huge temperature differences between night and day.
Another measure of Martian weather is air pressure. On Earth, the average air pressure is approximately 100 times what it is on Mars. Air pressure, as a result of temperature fluctuations, can be different depending on the locale being measured. Warmer temperatures cause air molecules to move faster, pushing on each other and causing air to expand. With fewer molecules occupying a given amount space, the air exerts less pressure. Conversely, cold air molecules will move slower, allowing more molecules to exist in a given amount space. This increase in weight allows more pressure to be exerted.
With the avalanche of information we are receiving from NASA and their study of our next door neighbor, knowing about the basic weather of Mars can only help lend context to any and all future discoveries made on this planet.