Standard sea-level conditions

Standard sea-level conditions, often referred to as standard atmospheric conditions or International Standard Atmosphere (ISA), are a set of idealized atmospheric conditions defined for the purpose of measurement and comparison. The conditions are typically specified at sea level and are assumed to be: - **Temperature:** 15 degrees Celsius (59 degrees Fahrenheit) - **Pressure:** 1013.25 hPa (hectopascals), or 1013.25 millibars, or 29.