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.
HBP at altitude usually returns to your baseline blood pressure after 1-2 weeks at altitude. One explanation for this is due to the higher levels of adrenaline or stress hormones in your body due to lower oxygen levels. Some persons with HBP, however, develop lower blood pressure on ascent to high altitude.