Notice that Mars' seasons last about twice as long as our seasons. Also visible on Mars are dark markings called maria or seas like the dark lunar features. Of course there are no water filled seas on Mars. The coloration appears to be in the soil itself, and seems to change in intensity with the seasons. On page 2 is a reproduction of a drawing I made of the Syrtis Major region of Mars in 1973.
Dust storms can obscure features on the face of Mars.
They are apt to happen near the start of the southern hemisphere summer. I saw one during the 1973 observing season. They appear light in color, but I first noticed one because the expected Martian features I was trying to see were missing. The famous Martian Canals are illusions. I noticed in my observation that I tended to see and draw circular or linear forms, and cab be seen with the two drawings of Mars that accompany this article.