Angeles climate also is home to people who thrive during the brief seasonal respite the gloom provides from the unending sunshine and clear skies. In the early 20th century, this phenomenon was sometimes known as the high fog. A long June Gloom season, extending late into the summer, is known as Summer Bummer. The negative effects of a long June Gloom on the coastal California tourism industry is often reported in the local news media. The phenomenon can be especially disorienting to visitors from inland areas who, coming from the summer heat, would not expect cool temperatures and clouds and fog at the beach. Formation The low-altitude stratus clouds that make up the June Gloom cloud layer form over the nearby ocean, and are transported over the coastal areas by the region's prevailing westerly winds. The sheet-like stratus clouds are almost uniformly horizontal, covering large areas but having relatively shallow depth of . These clouds begin to form when wind mixes moisture from the ocean surface into the air. The air cools and expands as it is mixed and moves upward, and this cooling increases the relative humidity. When the relative humidity reaches 100%, the water vapor condenses into liquid water droplets and the clouds begin to form. The stable top of the marine layer, a result of the temperature inversion, prevents any dry, warm air from above the inversion from mixing with the stratus deck. This confines the stratus deck to a relatively narrow vertical band in the atmosphere, allowing it to strengthen. The inversion layer is crucial to the formation of the marine stratus that produce June Gloom. Compression and warming of air sinking out of the North Pacific High-pressure system (which is strongest during the summer) meets with the rising, cooling air from the sea surface, producing a very stable layer of air that caps the cool air from rising any further. The strength of this subsidence inversion affects the strength of the marine layer, and how long it will take the clouds to dissipate. Additionally, the cool ocean water of the California Current, which flows out of the cold Gulf of Alaska, enhances the contrast between the cool air below the inversion layer and the warm air above it. A stronger inversion layer – one with a greater difference in temperature between the air above and the air below – often results in more and deeper