ABSTRACT
The part of the atmosphere that is of greatest importance to extensive air shower (EAS) development is the troposphere, characterized by a decreasing temperature with altitude, extending from ground level to a height of about 15 km. The troposphere is characterized by turbulent behavior that generates the well-known phenomenon of weather. It is often important in cosmic ray physics to determine the atmospheric depth along a line inclined to the vertical. This is called the “atmospheric slant depth”. The atmosphere affects optical EAS observation primarily by attenuating and scattering the produced Cherenkov or fluorescence light. Modern experiments using air fluorescence and Cherenkov light monitor variations in atmospheric transmission operate by placing calibrated “standard candles” at known distances from detectors. Optical detection of EAS properties must be performed in regions where aerosol scattering remains a small proportion of Rayleigh scattering. Aerosol scattering is often approximated using a spherical drop approximation and is then referred to as Mie scattering.
