The boundary between the stratosphere and the mesosphere. It occurs at an atmosphere height of approximately 50 km; however this depends on latitude. The atmosphere is characterized by a decrease in pressure with respect to increased altitude. More important, regions within the atmosphere, like the troposphere, stratosphere, and mesosphere, are distinguishable because of distinct temperature gradients with relatively well-defined starting and ending points. The stratopause is the highest portion of the stratosphere, with a temperature of approximately 0°C; the stratopause can also be described as the warmest region between the mesosphere and the stratosphere.