What is difference between Pressure base and atmospheric pressure?

Pressure base refers to a specific reference level used to measure pressure, typically set at sea level or another defined point, while atmospheric pressure is the weight of the air above a particular point in the atmosphere, measured in units like pascals or millibars. Atmospheric pressure varies with altitude and weather conditions, while pressure base is a fixed reference point. In engineering and meteorology, understanding both concepts is crucial for accurate measurements and calculations.