Yes, atmospheric pressure can effectively be considered zero at a certain altitude.
While atmospheric pressure never truly reaches absolute zero, it decreases exponentially with altitude. At the Kármán line, located 100 km (62 miles) above the Earth's surface, the air pressure is so low that it's widely accepted as the boundary where space begins. This point is often considered the effective "zero" for atmospheric pressure in practical terms.
Think of it this way:
- At sea level: We experience the full weight of the atmosphere above us, resulting in significant pressure.
- Atop a mountain: There's less atmosphere above, so the pressure is lower.
- In the upper atmosphere: The air becomes incredibly thin, and the pressure is negligible.
- At the Kármán Line (100km): For all intents and purposes, the atmospheric pressure is considered zero, marking the transition to outer space.
In summary, although trace amounts of gas particles may exist even beyond the Kármán line, the pressure they exert is so minimal that it is considered effectively zero for most practical applications.
