Here's why:

* Troposphere: This is the lowest layer of the atmosphere, extending from the Earth's surface up to about 7-15 km (4-9 miles) in altitude. It contains most of the atmosphere's mass and is where all weather phenomena occur. Mount Everest's peak is at approximately 8.85 km (5.5 miles), well within this layer.

* Other layers: The other layers of the atmosphere, the stratosphere, mesosphere, thermosphere, and exosphere, are located at much higher altitudes.