The average thermal energy of a particle in an ideal gas depends on temperature. We can pull average velocity out of the energy if we know the mass of the gas particle.

Thermal energy = kinetic energy

3/2 k_b T = 1/2 m v^2

Rearrange:

v = sqrt( 3 k_b T / m)

• k_b = boltzmann constant = 1.4e-23 J/K
• m for a nitrogen molecule = 28 amu = 4.6e-26 kg
• T in the stratosphere is around 220-270K, lets pick 250 arbitrarily

Plugging in yields v = 477 m/s. Oxygen would be slightly slower due to being more massive.

At sea level, the speed of sound is around 340m/s, and it decreases as you go up. In other words, the average air molecule is already bouncing around in the stratosphere at supersonic speeds. A collision with a supersonic aircraft would be absolutely unremarkable in terms of accelerating a gas molecule out of the atmosphere.

UV photochemistry and solar wind are the main ways gas is able to escape the atmosphere. Also, the above velocity is the average velocity. There are rare gas particles going much faster such that some gas can escape the atmosphere just by bouncing off other gas molecules ("thermal escape").

With cloning you get an exact copy, at least in terms of DNA sequence. This is done by copying a body cell called a "diploid cell," which has a full copy of an individual's DNA.

With parthenogenesis, you do not get an exact copy. You take two haploid gametes, aka sex cells, and implant one into the other similar to how a sperm implants into an egg. The difference is that in this case, it is two egg cells ("oocytes") from a single mother instead of a sperm and an egg from two different parents.

Most genes (with a few exceptions, particularly for male offspring) consist of two copies, one from the father and one from the mother. The grandfather and grandmother of the parthenogenetic offspring.

Whereas the mother has one copy each from the grandmother and grandfather (again, with some exceptions) the parthenogenetic offspring might get two grandmother copies, or two grandfather copies, or it might be the same as the mother with one copy of each. However, with how many genes there are, there is essentially a zero% chance the offspring gets one of each for every gene like the mother has. Thus, its DNA is different from the mother.

This is the same reason you are not a genetic copy of your brothers and sisters. In this case, there are 4 grandparents and 4 possible parings instead of 2 grandparents and 3 pairings for parthenogenesis.

Edit: perhaps an easier way to explain this. If two clones or two identical twins were to mate, their offspring would be genetically identical to parthenogenetic offspring. It is the most extreme form of inbreeding possible, but each offspring would still have unique DNA like brothers and sisters are unique from each other.