The mid-nineteenth century marked a significant milestone in atmospheric science, particularly with the advent of balloon-borne remote sensing. This period saw remarkable improvements in meteorological instruments and ballooning technology, enabling direct measurements of atmospheric conditions at high altitudes. Pioneering this field were French meteorologist Léon Teisserenc de Bort and German meteorologist Richard Aßmann, who independently utilized high-altitude hydrogen balloons to study the Earth’s atmosphere.
Starting in 1896, de Bort embarked on an ambitious project, launching hundreds of unmanned, instrumented weather balloons into the atmosphere. These balloons could reach altitudes of about 56,000 feet (17,000 meters), providing unprecedented insights into atmospheric structure. The early observations by these scientists led to the discovery of two distinct atmospheric layers. The lower layer, named the troposphere (from the Greek word “turning”), showed a gradual decrease in temperature with altitude, up to around 40,000 feet (12,000 meters). Above this layer, in the stratosphere (“spreading out”), temperatures remained relatively constant, even at the highest altitudes reached by their balloons.
Subsequent advancements in aerology, including higher-flying weather balloons, aircraft, sounding rockets, and orbital satellites, have significantly expanded our knowledge of Earth’s atmosphere. Contrary to the initial belief of two main layers, scientists now recognize five distinct layers: (1) the troposphere, extending to about 7 miles (12 kilometers) with the majority of the atmosphere’s mass; (2) the stratosphere, reaching up to 31 miles (50 kilometers) and warming at higher altitudes due to ozone; (3) the mesosphere, stretching up to 50 miles (80 kilometers) with decreasing temperatures; (4) the thermosphere, extending to 440 miles (700 kilometers), influenced by solar wind and Earth’s magnetic fields, and responsible for auroral displays; and (5) the exosphere, reaching up to about 6,200 miles (10,000 kilometers), where particles can escape into space or return along magnetic field lines.
