Clouds significantly influence radiative transfer in the atmosphere by creating large deviations from clear-sky fluxes. Over the past two decades, the radiative signatures of clouds on their surrounding have been extensively studied, highlighting the challenges of adequately defining clouds and distinguishing them from aerosols. These distinctions are important for accurately quantifying cloud and aerosol radiative effects and for remote sensing under clear-sky conditions of both the surface and atmosphere.

In this study, we take a step further by analyzing high-resolution multi-spectral images of cloud fields co-located with broadband top-of-the-atmosphere radiative fluxes. By adjusting the equation for radiative fluxes at the top of the atmosphere to explicitly include cloud effects in the  ''clear sky '' term, we can make use of CERES measurements together with MODIS high-resolution spectral data to quantify, for the first time, the net radiative effect of clouds within the inter-cloud zone. We find that the local radiative effect of this zone over the Ocean at noon is -7 to -10 W m^(-2) in the solar and +1–1.5 W m^(-2) in the longwave infrared.

These results indicate that a significant portion of the shortwave aerosol direct radiative effect is induced by clouds and show that the near-cloud radiative effect in the longwave infrared is equivalent to a substantial increase in greenhouse gases. We highlight the benefits that can be gained by categorizing the sky into three regimes — cloudy, cloud-influenced, and pure clear, and suggest new directions that can move beyond a discrete definition of the cloudy sky.