Fragmentation (and ablation)

When an object enters the atmosphere it experiments friction with air, giving birth to the beautiful phenomena of  meteors.
Friction also implies two fundamental physical phenomena that can lead to the complete destruction of the object, depending on the mass and on the type of body:  ablation and fragmentation.
In the first case (ablation) the heat caused by friction makes the body melt. Drops of melted material leave the main body of the falling object, eating it up. This process can bring to the complete destruction of the smallest bodies.
For bigger bodies, a consequence of friction is fragmentation, the destruction of the main body in smaller pieces. Friction acting on the surface of the body tends to augment the external pressure on the front side of the object, while on the rear face of the body, the pressure tends to reduce. If the consequant stress is bigger than the interior resistance of the material, it causes the impacting body to break up. 
Consequently, the area of the body on which frictions acts, grows up. For this reason, the process tends to continue, until the formed pieces slow down enough for the pressure on the surface of the body not to be able to make the process restart. Obviously, objects of different materials and masses act in different ways...
Whether the body is completely destroyed or not, different collateral effects follow the crossing of the atmosphere and can be explained as simple physical phenomena, such as the light trail left behind, or the bang that accompanies the phenomena.




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