Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

Tropospheric ducting occurs when a temperature inversion traps a radio wave in a layer of the lower atmosphere, allowing VHF, UHF, and microwave signals to travel hundreds or even thousands of miles beyond the normal line of sight. These temperature inversions most frequently form over large bodies of water. Over oceans or large lakes, cooler, moist air often gets trapped beneath a stable layer of warmer, dry air, creating a natural waveguide or 'duct.' Landmasses and mountain ranges generally disrupt these stable air layers due to uneven heating and rough terrain, making them poor environments for ducting.