There is no clear boundary, the atmosphere is gradually diluted with distance from the earth's surface, and there is still no consensus on what to consider as a factor in the beginning of the cosmos. If the temperature were constant, the pressure would vary exponentially from 100 kPa at sea level to zero. The International Aviation Federation, as the working boundary between the atmosphere and the cosmos, has established a height of 100 km (the Karman line), because at this altitude, to create an aerodynamic lift, it is necessary that the aircraft move with the first space velocity, which makes the airspace meaningless