What is the standard temperature at sea level?

The standard temperature at sea level is defined by the International Standard Atmosphere (ISA) as 15 degrees Celsius. This reference temperature is used globally for various scientific and engineering calculations, including those related to aviation and meteorology. The choice of 15 degrees Celsius reflects a balance of average conditions that can be expected at sea level, making it a reliable standard for professionals in fields dealing with atmospheric pressures and temperatures. This standard is not arbitrary; it is derived from extensive historical climate data and serves as a baseline for understanding how temperature varies with altitude and geographic location. The other temperature options do not meet this established standard, as they either represent temperatures that are higher or lower than the accepted mean sea level temperature in the ISA framework.