Kieffer, Hugh H.; Christensen, Philip R.; Titus, Timothy N. (August 17, 2006). "CO 2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap". Nature. Nature Publishing Group. 442 (7104): 793–796. Bibcode: 2006Natur.442..793K. doi: 10.1038/nature04945. PMID 16915284. S2CID 4418194. Jakosky, Bruce M.; Haberle, Robert M. (1990). "Year-to-year instability of the Mars Polar Cap". J. Geophys. Res. 95: 1359–1365. Bibcode: 1990JGR....95.1359J. doi: 10.1029/JB095iB02p01359.

It is now thought that ice accumulated when Mars' orbital tilt was very different from what it is now. (The axis the planet spins on has considerable "wobble", meaning its angle changes over time.) [120] [121] [122] A few million years ago, the tilt of the axis of Mars was 45 degrees instead of its present 25 degrees. Its tilt, also called obliquity, varies greatly because its two tiny moons cannot stabilize it like Earth's moon. The northern polar cap has a diameter of approximately 1,000km during the northern Mars summer, [109] a b Benson; etal. (2006). "Interannual variability of water ice clouds over major martian volcanoes observed by MOC". Icarus. 184 (2): 365–371. Bibcode: 2006Icar..184..365B. doi: 10.1016/j.icarus.2006.03.014.Martian storms are significantly affected by Mars' large mountain ranges. [104] Individual mountains like record holding Olympus Mons (26km (85,000ft)) can affect local weather but larger weather effects are due to the larger collection of volcanoes in the Tharsis region. Main article: Water on Mars The ice-filled Korolev crater near Mars's north pole is estimated to hold about 2,200km 3 (530cumi), comparable in volume to the Great Bear Lake.

Jakosky, Bruce M.; Phillips, Roger J. (2001). "Mars' volatile and climate history". Nature. 412 (6843): 237–244. Bibcode: 2001Natur.412..237J. doi: 10.1038/35084184. PMID 11449285. review article Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted theories include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils. [65] Several other explanations have been put forward, including those that involve water or even the growth of organisms. [66] [67] One of the major differences between Mars' and Earth's Hadley circulations is their speed [54] which is measured on an overturning timescale. The overturning timescale on Mars is about 100 Martian days while on Earth, it is over a year.

a b c d Spiga, A. (August 1, 2011). "Elements of comparison between Martian and terrestrial mesoscale meteorological phenomena: Katabatic winds and boundary layer convection". Planetary and Space Science. Comparative Planetology: Venus-Earth-Mars. 59 (10): 915–922. Bibcode: 2011P&SS...59..915S. doi: 10.1016/j.pss.2010.04.025. ISSN 0032-0633. National Space Science Data Center: Meteorology". Archived from the original on July 28, 2020 . Retrieved September 14, 2014. Mars is among the brightest objects in Earth's sky, and thus has been known from ancient times. Its high-contrast albedo features make it a common subject for viewing with a telescope. Since the late 20th century, Mars has been explored by uncrewed spacecraft and rovers, with the first flyby by the Mariner 4 probe in 1965, the first Mars orbiter by the Mars 2 probe in 1971, and the first landing by Viking 1 in 1976. As of 2023, there are at least 11 active probes orbiting Mars or at the Martian surface. Mars is an attractive target for human missions. A large intensifying dust storm began in late-May 2018 and had persisted as of mid-June. By June 10, 2018, as observed at the location of the rover Opportunity, the storm was more intense than the 2007 dust storm endured by Opportunity. [66] On June 20, 2018, NASA reported that the dust storm had grown to completely cover the entire planet. [67] [68]

Mars Weather". Centro de Astrobiología. 2015. Archived from the original on October 25, 2015 . Retrieved May 31, 2015.NASA Mars Rovers Braving Severe Dust Storms" (Press release). Jet Propulsion Laboratory. July 20, 2007.