Lockheed Martin has released Prepar3D v5.1 Hotfix 1. The new hotfix addresses many issues such as cloud issues with Enhanced Atmospherics, rendering issues and other weather-related issues.
Looking at the changelog of client fixes and improvements, Enhanced Atmospherics (EA) seems to have a large number of changes based on feedback. Issues with cloud aliasing have been reduced, along with flashing clouds, and shadow flashing. Furthermore, there has been additional configuration options to how clouds are generated. Other fixes include changes to fog/haze implementation, ambient lighting and also how some forms of vegetation is drawn in the simulator.
You can download the newly released hotfix for Prepar3D v5.1 from the Prepar3D website. A full download of Prepar3D v5.1 will need to be downloaded and the hotfix will be included. (Update: You can also download the client and scenery installers to grab the hotfix. The majority of the changes can be found in the client installer).
As usual, various third-party add-ons may need an update to be compatible with the new hotfix. For reference, the new Prepar3D version number is 188.8.131.52829.