Why do many meteors end their visible flights above 80 kilometres in altitude?

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Meteor and meteoroid The Cabin Creek meteorite, an iron (nickel-iron alloy) meteorite that was observed to fall in northwestern Arkansas on March 27, 1886. Its characteristic pattern of “thumbprint” dimples, or regmaglypts, is the result of melting and consequent ablation of its surface as it traveled through the atmosphere. The meteorite is likely a fragment of one of the M class asteroids, which show significant nickel-iron in their surface material.

Many meteors conclude their visible flight above 80 kilometres in altitude primarily due to the rapid release of kinetic energy upon entering the atmosphere. As a meteoroid encounters atmospheric gas molecules, friction converts its high-velocity kinetic energy into intense heat, which vaporizes and ionizes the object's surface material.1

This process leads to the destruction of most meteoroids through two main mechanisms:
* Ablation: The loss of surface mass through vaporization or the shedding of molten droplets.1
* Fragmentation: The physical breaking apart of the meteoroid caused by aerodynamic pressure that exceeds its internal crushing strength.1

Because this energy release is so significant, particularly for objects traveling at high velocities, the meteoroid is often destroyed before it can penetrate to lower altitudes.1