Why Is It Cold in the Bay Area Again
Most of the state has set record temperatures this summertime, but San Francisco has been cool and almost permanently cloudy considering of its marine layer. And while Southern California is setting water temperature records, I heard the bounding main surface temperature was 49 degrees at Bodega Bay in early on August. What'south going on? Why has it managed to exist so cool, or at to the lowest degree, normal, in this minor stretch of Northern California while it's then extremely hot everywhere else?
Indeed San Francisco weather is dominated by its marine layer, directly from the sea on the due west but also from the north due to the marine air that enters the Bay through the Gilded Gate gap. But in reality, the marine layer influences the coast all along California. The divergence is the condition of the local marine layer and how deep inland that influence reaches – which in the case of the San Francisco Bay is much more inland compared to other areas.
Roughly from the Monterey Bay all the manner to Cape Mendocino, the marine layer is particularly cold and foggy due to littoral upwelling. Littoral upwelling is the process past which the strong and persistent northwesterly winds bring deep and cold h2o to the surface at the coast. How they do that? With the assistance of the Earth'south rotation (an result chosen Coriolis): when surface h2o flows along the declension pushed by the winds, the Coriolis event then deflects the menstruation to the right in the Northern Hemisphere, which effectually our declension happens to be offshore. The displaced littoral water is and so replaced by water from depth, which is colder and incidentally full of nutrients that fuel our rich marine ecosystem. Once this deep h2o reaches the surface, it cools the air, also, leading to the germination of fog every bit water vapor condenses into droplets because colder air tin can "hold" less water than warm air.
Coastal upwelling occurs more often than not in spring and summer, causing windy, foggy and cold weather condition, especially in the Northern-Fundamental California coast where winds are strongest. This is why summers are puzzling in San Francisco, and why the famous quote, apparently wrongly attributed to Ernest Hemingway and Mark Twain, even so gets passed effectually so often: "The coldest winter I e'er saw was the summer I spent in San Francisco."
Littoral upwelling all the same occurs to the south, as the northwesterly wind blows all the way to Baja California, but it is weaker and the ocean water, even at depth, is warmer, and so it does not have the same cooling consequence over the coast as it does in Northern California. Likewise, Southern California atmospheric condition is more influenced by the Southwest climate than the northern part of the country. This combination allows Southern Californians to enjoy sunny and warm days at the beach during the summer, even on windy days. To sum information technology up: the northern and southern coasts enjoy unlike climates, and the North Coast is specially dissimilar from the rest of the state'southward climate.
And then in general, every summer there is a nice contrast between San Francisco and Southern California. Merely why does this year seem particularly extreme? Well, this is considering both locations are experiencing a change in conditions — but in reverse directions. The Southwest and California (every bit much of the world) experienced one of the hottest summers on tape, associated with rising global temperatures. But at the same fourth dimension, in Northern California we are experiencing a decade of strong summer upwelling caused by stiff winds. This summertime we had the fifth strongest summertime upwelling on record around Bodega Bay.
The northerly summer winds are themselves caused by an atmospheric loftier-pressure organisation over the ocean off California, and therefore linked to its strength and position. Scientists expect that the high-pressure level system will migrate north with climatic change, which will strengthen winds in northern areas. The strong summer winds nosotros are experiencing now are office of an increasing trend observed since the 1940s only in Northern California, which is consequent with what nosotros expect under rising global temperatures. So, yes, we are indeed experiencing more contrast betwixt San Francisco and Southern California in the summertime. And while information technology might non be every year, overall we wait it to happen more frequently.
Ask the Naturalist is a reader-funded bimonthly cavalcade with the California Center for Natural History that answers your questions nigh the natural globe of the San Francisco Bay Area. Have a question for the naturalist? Fill out our question class or email u.s.a. at atn at baynature.org!
Source: https://baynature.org/article/its-so-hot-everywhere-else-why-not-in-the-bay-area/
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