COPENHAGEN/FRANKFURT, Aug 12 - Orsted and RWE, the world's two largest offshore wind players, both suffered from lighter winds in the first half of the year, highlighting how profits in the booming industry remain tied to weather conditions. Denmark's Orsted said wind speeds in the April-June period were "significantly lower than normal" and ranked among the worst three quarters in over more than 20 years. As a consequence, it said it would likely hit only the lower end of its guided core profit range in 2021. Orsted was however confident that it wind speeds would return to more normal levels....