Earth's Atmosphere extends, gradually thinning, to 1,000 miles,
1/2 is below 3 1/2 miles.
Because of  Turbulence, composition to 45 miles is  78% Nitrogen, 21% Oxygen, .03% Carbon Dioxide, and  .04% Argon, Neon, Radon, Helium, Krypton, Xenon, Methane, Nitrous Oxide, & Ozone.
Also, up to 4% Water-Vapor, Dust, Salt, Carbon Monoxide, Micro-   Organisms, & Industrial Chemicals.
Above 500 miles are Helium & Hydrogen

TROPOSPHERE - Up to 5 miles above Poles & 11 miles above
Equator - Clouds, Weather, Heated by Earth Surface, Vertical Air Currents & Horizontal Winds
TROPOPAUSE - Boundary between Troposphere & Stratosphere
STRATOSPHERE -  Up to 30 miles.
Near weatherless, little Vertical Air motion, Temperature drop slows - increases near top
MESOSPHERE - 30 - 50 miles
Temp. drop from 30 to -100 F at top
THERMOSPHERE -  50 - 500 miles Ionized Particle Layers - Reflect Long Radio Waves,  E Layer 50-80 mi. up & F Layer 150-200 mi.,  Temp. varies (at 300 mi.) from 2,500+ F in Day to 300 at Nite,  Aurora occur
EXOSPHERE - 500 - 1,000 miles
Ionized Atomic Hydrogen & Helium, 4,500 degrees F in Day, -450 F at Nite