Cirrus clouds on Mars.
On September 18, 2008, the Martian Lander Phoenix took a time-lapse photograph of a group of cirrus clouds moving across the Martian sky using LiDAR. Near the end of its mission, the Phoenix Lander detected more thick cirrus clouds close to the north pole of Mars. Over the course of several days, these clouds thickened, lowered, and eventually began snowing. The total precipitation was only a few thousandths of a millimeter. James Whiteway from York University concluded that “precipitation is a component of the [Martian] hydrologic cycle.” These clouds formed during the Martian night in two layers, one around 4,000 m (13,000 ft) above ground and the other at surface level. The clouds lasted through early morning before being burned away by the sun. The crystals in these cirrus clouds were formed at a temperature of −65 °C (−85 °F), and they were shaped roughly like ellipsoids 0.127 millimeters long and 0.042 millimeters wide.