* Atomic Oxygen (O) - This is the most abundant constituent of the thermosphere.
* Helium (He) - Helium is the second most abundant gas in the thermosphere and exosphere.
* Hydrogen (H) - Hydrogen becomes the dominant gas in the exosphere.
* Nitrogen (N) - While not as abundant as oxygen, nitrogen still exists in the upper atmosphere, albeit in a much lower concentration than in the lower atmosphere.
* Carbon Dioxide (CO2) - Carbon dioxide is present in the upper atmosphere, but its concentration is much lower than in the troposphere.
Other gases present in trace amounts include:
* Argon (Ar)
* Neon (Ne)
* Sodium (Na)
* Iron (Fe)
It's important to remember that the composition of the upper atmosphere can vary depending on factors like altitude, latitude, and solar activity.
