Probability Definition. The probability of an event is a number between $0$ to $1$ which measures the chance of that event occurring. The likelihood of the occurrence of the event increases as the probability varies from $0$ to $1$. The probability of the occurrence of an impossible event is $0$ and that of a certain to occur event is $1$.
As altitude increases, air pressure decreases. Gravity causes the atmosphere to become heavier the closer you are to the ground. The atmosphere may seem weightless but all the â¦ air molecules add up to a tremendous amount of mass.
When ambient air pressure is higher (for a given temperature), the density of the air will be higher, so buoyancy will be increased - just slightly. There is pressure above you pushing down and trying to increase your weight, but there is just as much pressure below you pushing up trying to decrease your weight. So they ALMOST balance out. But, there's actually slightly more air pressure below you than above you, so the overall total effect is that your weight actually gets decreased. This is the upward thrust you speak of, otherwise known as buoyancy. It takes the pressure above you into account. Thanks , for appropriate explanation.