Polar orbiting satellites closely parallel the earth's meridian lines, thus having a highly inclined orbit close to 90°. They pass over the north and south poles each revolution. As the earth rotates to the east beneath the satellite, each pass monitors an area to the west of the previous pass at intervals of roughly 90 to 100 minutes.
These strips can be pieced together to produce a picture of a larger area. Polar satellites have the advantage of photographing clouds directly beneath them. Geostationary satellite images of the polar regions are distorted because of the low angle the satellite sees the region. Polar satellites also circle at a much lower altitude (about 850km, 530mi) providing more detailed information about violent storms and cloud systems. Various environmental and weather satellites such as the NOAA and TIROS series, or the METEOR satellites are included in this category.