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1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteIn one NASA simulation of northern summer near Mars’s equator, water-ice clouds build slowly overnight, reach their greatest thickness just before sunrise, then disperse as daytime warming changes the conditions that let them grow. They start to reform around dusk. That is a modeled example, not a timetable that applies to every Martian cloud: cloud type, season, location, altitude and local conditions all matter.
How the overnight cloud cycle works
Mars has an active water cycle. Water moves between the surface and atmosphere, travels with atmospheric circulation and can return to the ground as frost or snow. NASA identifies the north residual water-ice cap as the main current atmospheric water source described in its water-cycle overview. During northern summer, seasonal carbon-dioxide ice retreats, exposing water ice that can sublimate into vapor. The regolith may also contribute water.
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Clouds form when water vapor condenses onto ice nuclei and the temperature and pressure make condensation and growth possible. Dust in Mars’s atmosphere can provide those nuclei. Overnight cooling can favor ice-cloud growth when vapor and nuclei are present; daylight warming can reverse those favorable conditions in some settings.
NASA’s 2019 supercomputer simulation depicts the sequence near the equator in northern summer: gradual growth overnight, maximum thickness shortly before sunrise, quick dispersal as the day warms, and renewed formation around dusk. Several peaks of the Tharsis Montes volcano chain rise through the modeled cloud layer.
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Why this is not a universal sunrise-to-sunset rule
Mars’s cloud patterns vary with season and geography. Orbital observations show increased activity for a few months around northern summer solstice in a band from about 10° south to 30° north latitude. Jezero crater, at roughly 18° north, lies within that band, which makes it a useful location for Perseverance to observe the seasonal activity. NASA describes this pattern in “Cloudy Sols Are Here Again”.
Other clouds appear under different conditions. Curiosity has observed twilight clouds during early southern fall: high-altitude carbon-dioxide ice clouds alongside lower water-ice clouds. NASA says it remains unexplained why carbon-dioxide twilight clouds have not been seen at other rover locations. Gravity-wave cooling is one proposed explanation, not a settled answer.
What Martian clouds are made of—and where they form
Modern Mars has both water-ice clouds and carbon-dioxide-ice clouds. NASA says carbon-dioxide clouds form at higher altitudes and lower temperatures than water-ice clouds. In the particular Curiosity twilight observation NASA describes, carbon-dioxide clouds were about 60–80 kilometers (37–50 miles) above the surface, while water-ice clouds were around 50 kilometers (31 miles) high. Those measurements describe that observation, not every cloud on Mars.
In a separate report about Mars’s twice-daily atmospheric temperature pattern, NASA’s Jet Propulsion Laboratory discussed equatorial water-ice clouds at altitudes of 10–30 kilometers (6–19 miles). The range belongs to that report’s observations and should not be conflated with Curiosity’s higher-altitude twilight clouds.
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Present-day Martian clouds are thin compared with many clouds on Earth because the atmosphere contains little water. Thin does not mean unimportant: clouds can warm or cool the atmosphere and surface depending on their altitude, location and optical properties. Their motion also helps researchers estimate high-altitude wind speed and direction, which are difficult to measure directly.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How clouds affect Mars’s temperatures and climate
Clouds influence the planet beyond the visible sky. NASA modeling indicates that their radiative effects can substantially alter the atmosphere’s temperature structure and global wind systems, which in turn affect how water moves around Mars. Whether a cloud warms or cools depends on its properties and where it is.
In a 2013 account of Mars Reconnaissance Orbiter Mars Climate Sounder observations, JPL reported that atmospheric temperatures can rise and fall twice daily—a pattern called a semi-diurnal atmospheric tide. The reported swings reached as much as 58°F (32 kelvins). Researchers found that including the radiative effects of water-ice clouds in climate models reproduced aspects of the pattern. Armin Kleinboehl, the study’s lead author and a JPL researcher, described the observations this way: “We see a temperature maximum in the middle of the day, but we also see a temperature maximum a little after midnight.”
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Clouds can also affect the surface locally. NASA’s Perseverance science team notes that clouds around sunset emit thermal radiation downward, so the ground cools more slowly after sunset than it would under clear skies.
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Sources and further reading
- NASA: Water Cycle (page updated 2023)
- NASA: A Cloudy Martian Night, Through the Eyes of a Supercomputer (2019)
- NASA Science: Cloudy Sols Are Here Again (updated 2024)
- NASA: NASA’s Curiosity Rover Captures Colorful Clouds Drifting Over Mars (2024)
- NASA Jet Propulsion Laboratory: Mars Water-Ice Clouds Are Key to Odd Thermal Rhythm (2013)
- NASA Advanced Supercomputing: Simulating the Water Cycle and Cloud Formation on Mars
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