As part of the FIRE III experiment, some 50 tethered balloon soundings were carried out from the Arctic sea ice at the SHEBA ice camp during May 1998. The main purpose of the soundings was to measure vertical profiles of (visible) actinic flux under different meteorological conditions, in particular the effect of a high surface and cloud albedo on the actinic flux. Moreover, actinic flux measurements at the surface were performed during the whole period. The actinic flux is a radiometric quantity which is defined as the radiance integrated over all solid angles per unit area. The 4-pi radiometer was designed to be suspended under a balloon and has a spectral response in the visible light band (400-750 nm). Vertical profiles of actinic flux under clear sky conditions and Arctic stratus will be discussed. In clouds, a strong increase with height in the actinic flux was observed. However, none of the observations shows a local maximum in actinic flux near the top of the cloud. This peak is generally explained by the fact that collimated, direct solar radiation, is converted to isotropic light in clouds, such that the actinic flux is multiplied by a factor 2 cos z, with z the zenith angle. However, at the measurement site the zenith angle around solar noon was approximately 60°, and therefore the maximum 'enhancement' factor was about 1. Due to the high albedo of the ice surface, the actinic fluxes above clouds and under clear sky conditions were about the same.