Polar Orbiting Environmental Satellites (POES) are placed in circular sun-synchronous (see below) orbits and their altitudes usually range from 700 to 800 kilometers, with orbital periods of 98 to 102 minutes.
Image provided by: National Climatic Data Center

POES satellites include: Defense Meteorological Satellite Program (DMSP), Landsat, SPOT and NOAA Polar-orbiting Operational Environmental Satellites (NPOES). The DMSP and NPOES satellites are operational meteorological satellites. Imagery from successive orbits overlay each other, providing global daily coverage from each satellite. Commercial polar orbiters like Landsat and SPOT, on the other hand, are intended for geophysical remote sensing, with an emphasis on high-resolution and multispectral imagery, at the cost of daily global coverage.