In which part of the atmosphere does temperature decrease with increasing height?

The stratosphere

The atmosphere is layered, and these layers correspond with how the atmosphere's temperature changes with altitude. By understanding the way temperature changes with altitude, we can learn a lot about how the atmosphere works. For example, the reason that the weather takes place in the lowest layer is that the Earth's surface is the atmosphere's primary heat source. Heating the lowest part of the atmosphere places warm air beneath colder air, an unstable situation that can produce violent weather. Interesting things happen higher in the atmosphere, like the beautiful aurora, which light up the sky with brilliant flashes, streaks and rolls of white or colored light.