Atmospheric balloon soundings have been made since the end of the 19th century. In recent decades, specific upper-air radiosonde measurements have become important for climate monitoring and atmospheric research. Here we show profiles of solar and terrestrial radiation measured with balloon-borne radiometers through cloud-free and cloudy atmospheres, which experimentally demonstrate the greenhouse effect by water vapor in the Earth’s atmosphere. Absorption and reflection of solar shortwave radiation in the atmosphere and on the ground are shown. Thermal longwave radiation, emitted from Earth’s surface and then absorbed and reemitted in the atmosphere, shows varying absorption/reemission of upward/downward longwave fluxes due to changing temperature and water vapor. Clouds more strongly absorb upward and increase downward longwave radiation. Thermal emission into space is shown to be reduced by water vapor and clouds. Measured radiation profiles are compared to numerically calculated radiation profiles.