What layer are most gasses found in the atmosphere?

Most gases in the atmosphere are found in the troposphere, which is the lowest layer, extending from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) high. This layer contains approximately 75% of the atmosphere's mass and is where weather phenomena occur, as well as where most of the water vapor is located. Above the troposphere lies the stratosphere, which contains the ozone layer but has significantly less water vapor.