Satellite images sometimes seem washed out or foggy, as atmosphere absorbs and scatters light on its way to the ground. We can correct for this to get clearer images using atmospheric correction. ESA provides a Sen2Cor processor, that applies atmospheric correction to the input Sentinel-2 L1C data with global coverage. The resulting product is called S2L2A data. To use Atmospheric correction, use the Sentinel-2 L2A (S2L2A) data collection.
Below, you can see the difference atmospheric correction makes. The first image of Marseille was made in EO Browser using S2L1C data, and the lower image was made using S2L2A atmospheric correction.