Does Mars have a Water Cycle?

Yes. There is a lot of water-ice in the polar caps of Mars, and the amount varies with the seasons. When the caps melt, the ice usually sublimes into the atmosphere rather than flowing as a liquid, because the temperatures are too low for liquid water to exist there.

See

http://en.wikipedia.org/wiki/Climate_of_Mars#Polar_caps

My addition would be that the water as ice evaporates rather than sublimes. I am sure it will return as ice because of the pressure/temperatre on Mars, but you can't assume that. In the same way on Earth colloquially we might say that snow 'sublimes', but as this is a science question then the correct term is evaporation.

In your answer you might want to point out that some water cycle steps such as plant transpiration are not present on Mars.

http://www.merriam-webster.com/dictionary/sublime?show=0&t=1317053824

Yes, Mars does have a water cycle, although it is significantly different from Earth's water cycle. To understand this, let's explore the water cycle on Earth and then compare it to Mars.

On Earth, the water cycle begins with the process of evaporation. The heat from the sun causes water from oceans, lakes, and rivers to turn into vapor and rise into the atmosphere. This water vapor then cools down and condenses into clouds. Eventually, the tiny droplets in the clouds come together and form larger water droplets, resulting in precipitation, such as rain or snow. The water then returns to the Earth's surface, either by falling directly or being absorbed into the ground. From there, it can flow into rivers, lakes, and oceans, and the cycle continues.

On Mars, the water cycle operates differently due to several key factors. First, the Martian atmosphere is much thinner than Earth's, with around 1% of the atmospheric pressure. This means that liquid water cannot exist on the surface for long periods because it would either freeze or, more commonly, rapidly evaporate into the thin atmosphere.

However, Mars does have water in the form of ice at its polar caps and in specific regions below the surface. During warmer seasons, some of this ice sublimates directly from a solid state into a gas, bypassing a liquid phase. This water vapor can then escape into the atmosphere.

Additionally, Mars occasionally experiences weather phenomena that are similar to Earth's water cycle, but on a much smaller scale. For example, cloud formations, mainly consisting of water ice crystals, have been observed in the Martian atmosphere. There is also evidence of frost and snowfall in some areas during Martian winters.

To directly answer your question, while Mars does have a water cycle, it is not as active or prominent as Earth's. The scarcity of liquid water and the thin atmosphere limit the extent and complexity of the Martian water cycle.