This image of a crater rim strikingly shows what appear to be bright white flows coming from gullies in the crater wall. However, HiRISE has been watching these gullies for some time (going all the way back to our first observation in 2012) and the flow features have been there for years. The new aspect is the bright white coloration, which is frost.
This is the earliest in the springtime that this area has been observed, and just like some winter mornings here on Earth, the conditions on Mars can be just right for frost to form. The interesting thing is that the frost appears on the gully deposits and not as much on the surrounding rock, indicating the physical properties of the gully deposits are different. [More at link]