The latitude effect in cosmic rays at altitudes up to 29,000 feet

Abstract

Accurate measurements with Neher recording electroscopes have been made both in Peru and in the Philippines on the cosmic-ray ionization of the atmosphere up to altitudes of 29,000 feet, with the following results: (1) In both localities the ionization rises essentially exponentially following a coefficient μ=0.50 per meter of water. This means that in the equatorial belt the ionization at 29,000 feet (two-thirds of the way to the top of the atmosphere) is about 50 ions per cc per sec., or half its value at the same altitude in the temperate zone. (2) If any longitude effect such as that which we have proved to exist at sea level exists at altitudes of 26,000 feet, it is inside the limits of our observational uncertainty, about 5 percent.