Final answer:
Standard surface pressure refers to the average atmospheric pressure at sea level, equivalent to 1 atm, 760 mmHg, 101.325 kPa, or 1.01 × 105 N/m². At higher altitudes, such as 30,000 feet, the pressure is much lower. Atmospheric pressure can be affected by altitude, temperature, and gravity variations.
Step-by-step explanation:
Standard surface pressure, commonly known as standard atmospheric pressure, is defined as the pressure exerted by the atmosphere at sea level. It is commonly measured as 1 atmosphere (atm), which is equivalent to 760 mmHg (millimeters of mercury), 101.325 kPa (kilopascals), or 1.01 × 105 N/m² (newtons per square meter). Atmospheric pressure decreases with altitude, and at an altitude of 30,000 feet, the pressure is significantly lower than at sea level.
At an altitude of 1500 m (about 5000 ft), the atmospheric pressure might be around 8.59 × 104 N/m², while at 3000 m (about 10,000 ft) it could be approximately 7.00 × 104 N/m². These pressures are about 80% and lower of the standard atmospheric pressure at sea level, respectively. Moreover, for significant figure purposes, the standard pressure of 760 mm Hg has three significant figures.
It is important to note that atmospheric pressure is not constant and can vary due to weather conditions and altitude. For every 8800 meters, the air pressure drops by about one-third of its value at sea level, although this is a rough estimate as it assumes a constant temperature and ignores changes in gravity at high altitudes, which are not strictly correct.