1.- On the history palette, once again we click on the empty gray box next to the step where we are happy how our lower part of the picture looks. The History Brush Tool icon will appear here. 2.- Now we travel back in time, in our history palette were the sky looked the way we wanted. We select this step just by clicking on it. 3.- We make sure to select the History Brush Tool. Again, the shortcut is "Y", just in case you didn't remember.