106-418: June Gloom is a mainly Southern California term for a weather pattern that results in cloudy , overcast skies with cool temperatures during the late spring and early summer. While it is most common in the month of June, it can occur in surrounding months, giving rise to other colloquialisms , such as “Graypril,” “May Gray,” “No-Sky July,” “Fogust”, and “Summer Bummer”. Low-altitude stratus clouds form over
212-654: A continental shelf are often warmer. Onshore winds can cause a considerable warm-up even in areas where upwelling is fairly constant, such as the northwest coast of South America . Its values are important within numerical weather prediction as the sea surface temperature influences the atmosphere above, such as in the formation of sea breezes and sea fog . It is very likely that global mean sea surface temperature increased by 0.88°C between 1850–1900 and 2011–2020 due to global warming , with most of that warming (0.60°C) occurring between 1980 and 2020. The temperatures over land are rising faster than ocean temperatures . This
318-644: A California earthquake forecast, which models earthquake occurrence in California. This is a partial list of earthquakes in Southern California. For a full list, see List of earthquakes in California . Note: Earthquakes with epicenters in the Los Angeles Metro Area are marked with the (#) symbol. Other earthquakes mentioned indicates shaking was felt in the region. As of the 2020 United States Census , Southern California has
424-420: A June Gloom day usually are at their maximum at dawn, when the surface air is at a minimum temperature and the temperature difference in the inversion layer is at its maximum. The air beneath the inversion base being at its coolest also makes it likely that it will be saturated with a relative humidity of 100%. A sea breeze , which is caused by the temperature and pressure difference between warm areas inland and
530-658: A M w 6.7 earthquake or greater, such as the San Andreas Fault , which can produce M w 8.0 or greater. The largest known earthquake in California was the 1857 Fort Tejon earthquake that ruptured 200+ miles (320+ kilometers) of the San Andreas Fault from Parkfield to Wrightwood . With a recurrence interval of roughly 150 years, this part of the San Andreas fault is well within its window to produce another large earthquake. Along with
636-530: A fraction of a millimetre thick) in the infrared or the top centimetre or so in the microwave are also used, but must be adjusted to be compatible with the bulk temperature." The temperature further below that is called ocean temperature or deeper ocean temperature . Ocean temperatures (more than 20 metres below the surface) also vary by region and time, and they contribute to variations in ocean heat content and ocean stratification . The increase of both ocean surface temperature and deeper ocean temperature
742-418: A greater difference in temperature between the air above and the air below – often results in more and deeper marine layer clouds that persist longer into the day. Upwelling of colder-than-normal ocean water, associated with a La Niña , can strengthen this effect even more. Once this marine layer has formed, the prevailing westerly winds advect the clouds over the coastal lands. The extent of inland advection
848-405: A higher altitude (e.g., at the 500 hPa level, or 5.9 km) can lead to tropical cyclogenesis at lower water temperatures, as a certain lapse rate is required to force the atmosphere to be unstable enough for convection. In a moist atmosphere, this lapse rate is 6.5 °C/km, while in an atmosphere with less than 100% relative humidity , the required lapse rate is 9.8 °C/km. At
954-645: A lesser degree due to its greater thermal inertia . On calm days, the temperature can vary by 6 °C (10 °F). The temperature of the ocean at depth lags the Earth's atmosphere temperature by 15 days per 10 metres (33 ft), which means for locations like the Aral Sea , temperatures near its bottom reach a maximum in December and a minimum in May and June. Near the coastline, some offshore and longshore winds move
1060-469: A one-day lag. NOAA's GOES (Geostationary Orbiting Earth Satellites) satellites are geo-stationary above the Western Hemisphere which enables them to deliver SST data on an hourly basis with only a few hours of lag time. There are several difficulties with satellite-based absolute SST measurements. First, in infrared remote sensing methodology the radiation emanates from the top "skin" of
1166-611: A population of 23,762,904. Despite a reputation for high growth rates, Southern California's population has grown slower than the state average since the 2000s. This is due to California's growth becoming concentrated in the northern part of the state as result of a stronger, tech-oriented economy in the Bay Area and an emerging Greater Sacramento region. Southern California consists of one Combined Statistical Area , eight Metropolitan Statistical Areas , one international metropolitan area , and multiple metropolitan divisions. The region
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#17327796182181272-473: A population of approximately 4 million, Los Angeles is the most populous city in California and the second most populous in the United States. South of Los Angeles and with a population of approximately 1.4 million is San Diego, the second most populous city in the state and the eighth most populous in the nation. The counties of Los Angeles , San Diego , Orange , Riverside , and San Bernardino are
1378-521: 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
1484-536: A weak June Gloom morning, the clouds and fog may only be present within a mile or two of the coastline, affecting only the beach cities. A combination of atmospheric and oceanic conditions must be just right in order for June Gloom to form, and these conditions usually align only around May and June of each year. These include the marine layer effect common to the West Coast of the United States , an atmospheric inversion caused by subsidence of high-pressure air from
1590-769: A whole enacted the Alquist Priolo Special Studies Zone Act in the wake of the 1971 San Fernando earthquake . The act prohibits new construction of residential buildings closer than 50 feet (15 m) from a surface rupturing active fault zone. In addition, the act improved safety by requiring new structures (both residential and commercial) to be seismically retrofitted. It also required existing infrastructure to comply. Since 1972, numerous large magnitude earthquakes have struck Southern California with little widespread damage in part due to act. However, exceptions can be noted for epicenters that lie directly on top of densely populated regions such as
1696-492: Is 5 years. When this warming or cooling occurs for only seven to nine months, it is classified as El Niño/La Niña "conditions"; when it occurs for more than that period, it is classified as El Niño/La Niña "episodes". The sign of an El Niño in the sea surface temperature pattern is when warm water spreads from the west Pacific and the Indian Ocean to the east Pacific. It takes the rain with it, causing extensive drought in
1802-502: Is also home to a large surf and skateboard culture. Companies such as Vans , Volcom , Quiksilver , No Fear , Stüssy , RVCA , and Body Glove are all headquartered there. Skateboarder Tony Hawk ; surfers Rob Machado , Timmy Curran , Bobby Martinez , Pat O'Connell , Dane Reynolds , and Chris Ward live in Southern California. Some of the most famous surf locations are in Southern California as well, including Trestles , Rincon , The Wedge , Huntington Beach , and Malibu . Some of
1908-513: Is also known for its mountain resort communities, such as Big Bear Lake , Lake Arrowhead , and Wrightwood , and their ski resorts, like Bear Mountain , Snow Summit , Snow Valley Mountain Resort , and Mountain High . The inland desert city of Palm Springs is also popular. Southern California is generally considered the area of California south of the latitude 35°45', approximately one-third of
2014-411: Is an important effect of climate change on oceans . The extent of the ocean surface down into the ocean is influenced by the amount of mixing that takes place between the surface water and the deeper water. This depends on the temperature: in the tropics the warm surface layer of about 100 m is quite stable and does not mix much with deeper water, while near the poles winter cooling and storms makes
2120-500: Is an important driver of North Atlantic SST and Northern Hemisphere climate, but the mechanisms controlling AMO variability remain poorly understood. Atmospheric internal variability, changes in ocean circulation, or anthropogenic drivers may control the multidecadal temperature variability associated with AMO. These changes in North Atlantic SST may influence winds in the subtropical North Pacific and produce warmer SSTs in
2226-687: Is an important government, arts and entertainment, and retail district. Downtown San Diego is the CBD of San Diego, though the city is filled with business districts. These include Carmel Valley , Del Mar Heights , Mission Valley , Rancho Bernardo , Sorrento Mesa , and University City . Most of these districts are located in Northern San Diego and some within North County regions. Los Angeles Orange County Riverside & San Bernardino San Diego Southern California
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#17327796182182332-408: Is because the ocean absorbs about 90% of excess heat generated by climate change . Sea surface temperature (SST), or ocean surface temperature, is the water temperature close to the ocean 's surface. The exact meaning of surface varies according to the measurement method used, but it is between 1 millimetre (0.04 in) and 20 metres (70 ft) below the sea surface. For comparison,
2438-410: Is home to Los Angeles International Airport , the second-busiest airport in the United States by passenger volume (see World's busiest airports by passenger traffic ) and the third-busiest by international passenger volume (see Busiest airports in the United States by international passenger traffic ); San Diego International Airport , the busiest single-runway airport in the world; Van Nuys Airport ,
2544-568: Is home to two extended metropolitan areas that exceed five million in population. These are the Greater Los Angeles Area at 17,786,419, and San Diego–Tijuana at 5,105,768. Of these metropolitan areas, the Los Angeles-Long Beach-Santa Ana metropolitan area , Riverside-San Bernardino-Ontario metropolitan area , and Oxnard-Thousand Oaks-Ventura metropolitan area form Greater Los Angeles; while
2650-453: Is limited by southern California's coastal mountain ranges. The winds will continue to push the cloud layer onshore until they encounter mountains at or above the altitude of the clouds themselves, with the mountains then preventing any further inland progress of the marine layer. The foothill regions of these mountains experience some of the thickest fog and drizzle, as they are essentially in the clouds at this point. The marine layer clouds of
2756-401: Is low to moderate depending on the area. Rain is infrequent, but is often heavy when it does occur, making flash floods an aspect of living in Southern California. This climatic pattern was alluded to in the hit song " It Never Rains (In Southern California) ". While snow is very rare in lower elevations, mountains above 5,000 feet (1,500 m) receive plentiful snowfall in the winter. Since
2862-656: Is made by sensing the ocean radiation in two or more wavelengths within the infrared part of the electromagnetic spectrum or other parts of the spectrum which can then be empirically related to SST. These wavelengths are chosen because they are: The satellite-measured SST provides both a synoptic view of the ocean and a high frequency of repeat views, allowing the examination of basin-wide upper ocean dynamics not possible with ships or buoys. NASA's (National Aeronautic and Space Administration) Moderate Resolution Imaging Spectroradiometer (MODIS) SST satellites have been providing global SST data since 2000, available with
2968-813: Is maintained by the National Data Buoy Center (NDBC). Between 1985 and 1994, an extensive array of moored and drifting buoys was deployed across the equatorial Pacific Ocean designed to help monitor and predict the El Niño phenomenon. Weather satellites have been available to determine sea surface temperature information since 1967, with the first global composites created during 1970. Since 1982, satellites have been increasingly utilized to measure SST and have allowed its spatial and temporal variation to be viewed more fully. Satellite measurements of SST are in reasonable agreement with in situ temperature measurements. The satellite measurement
3074-407: Is medium confidence that the tropical Pacific will transition to a mean pattern resembling that of El Niño on centennial time scale, but there is still high uncertainty in tropical Pacific SST projections because it is difficult to capture El Niño variability in climate models. Overall, scientists project that all regions of the oceans will warm by 2050, but models disagree for SST changes expected in
3180-506: Is the temperature of ocean water close to the surface. The exact meaning of surface varies in the literature and in practice. It is usually between 1 millimetre (0.04 in) and 20 metres (70 ft) below the sea surface. Sea surface temperatures greatly modify air masses in the Earth's atmosphere within a short distance of the shore. The thermohaline circulation has a major impact on average sea surface temperature throughout most of
3286-539: The 2020 census . The sparsely populated desert region of California occupies a significant portion (part of which has even been proposed to be split into a new county due to cultural, economic and geographic differences relative to the rest of the more urban region) of the area: the Colorado Desert , along with the Colorado River , is located on Southern California's eastern border with Arizona , and
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3392-605: The El Centro metropolitan area and San Diego-Carlsbad-San Marcos metropolitan area form the Southern Border Region . North of Greater Los Angeles are the Santa Barbara , San Luis Obispo , and Bakersfield metropolitan areas. Los Angeles (with a population of approximately 3.9 million people) and San Diego (at nearly 1.4 million people) are the two largest cities in all of California, and are among
3498-483: The Inland Empire (another large metropolitan area). The region generally contains ten of California's 58 counties: Los Angeles , San Diego , Orange , Riverside , San Bernardino , Kern , Ventura , Santa Barbara , San Luis Obispo , and Imperial counties. Although geographically smaller than Northern California in land area, Southern California has a higher population, with 23.76 million residents as of
3604-709: The Los Angeles metropolitan area ( Los Angeles and Orange counties, with 13.3 million people), the Inland Empire ( Riverside and San Bernardino counties, including the Coachella Valley cities, with 4.3 million people), and the Oxnard–Thousand Oaks–Ventura metropolitan area (0.8 million people). In addition, Southern California contains the San Diego metropolitan area with 3.3 million people, Bakersfield metro area with 0.9 million, and
3710-717: The Mojave Desert shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border . Southern California encompasses eight metropolitan areas (MSAs), three of which together form the Greater Los Angeles Combined Statistical Area (CSA) with over 18 million people, the second-biggest CSA after the New York CSA . These three MSAs are
3816-760: The Newport–Inglewood-Rose Canyon Fault (located adjacent to SoFi Stadium and responsible for Signal Hill ), the Elsinore Fault (created Lake Elsinore ), the Garlock Fault (which marks boundary between of the Sierra Nevada and the Mojave Desert ), and the Hollywood fault (which is within feet of Capitol Records and is roughly parallel to Hollywood Boulevard ). The United States Geological Survey (USGS) has released
3922-779: The San Diego metropolitan area as they do with the Inland Empire . To the east, the United States Census Bureau considers the San Bernardino and Riverside County areas, Riverside-San Bernardino area as a separate metropolitan area from Los Angeles County. Newly developed exurbs formed in the Antelope Valley , north of Los Angeles, the Victor Valley , and the Coachella Valley with the Imperial Valley . Also, population growth
4028-673: The San Fernando Valley and San Gabriel Valley , even extending into the Santa Clarita Valley and Inland Empire on exceptionally strong June Gloom mornings. If conditions are not as strong, the Basin may be filled while the valleys may be clear. It is not uncommon for motorists to drive over the Sepulveda Pass from the clear, sunny San Fernando Valley and plunge into a cloudy, fog-filled Los Angeles. On
4134-422: The San Fernando Valley . The area of Santa Monica and Venice (and perhaps some of Culver City) is informally referred to as "Silicon Beach" because of the concentration of financial and marketing technology-centric firms located in the region. The San Bernardino-Riverside Area maintains the business districts of Downtown San Bernardino , Hospitality Business/Financial Centre , University District which are in
4240-480: The Santa Barbara , San Luis Obispo , and El Centro (Imperial County) metropolitan areas. The Southern California Megaregion (or megalopolis ) is larger still, extending northeast into Las Vegas , Nevada and south across the Mexican border into Tijuana . Within Southern California are two major cities, Los Angeles and San Diego , as well as three of the country's largest metropolitan areas . With
4346-526: The Transverse and Peninsular Ranges with their peaks, and into the large and small interior valleys, to the vast deserts of California . Note: Plate boundary faults are indicated with a (#) symbol. Each year, Southern California has about 10,000 earthquakes. Nearly all of them are too small to be felt. Only several hundred have been greater than magnitude (M w ) 3.0, and only about 15–20 have been greater than M w 4.0. California as
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4452-403: The entertainment industry . Other industries include software, automotive, aerospace, finance, biomedical, ports and regional logistics. The region was a leader in the housing bubble from 2001 to 2007, and has been heavily impacted by the housing crash. Since the 1920s, motion pictures, petroleum, and aircraft manufacturing have been major industries. In one of the richest agricultural regions in
4558-444: The sea surface skin temperature relates to the top 20 or so microns of the ocean's surface. The definition proposed by IPCC for sea surface temperature does not specify the number of metres but focuses more on measurement techniques: Sea surface temperature is "the subsurface bulk temperature in the top few metres of the ocean, measured by ships, buoys and drifters. [...] Satellite measurements of skin temperature (uppermost layer;
4664-603: The subtropical ridge , and sufficiently cool ocean water off the coast. The June Gloom pattern is also enhanced by the Catalina eddy local to southern California. The months of May and June are typically the cloudiest months of the year in coastal southern California, having only 59% and 58% sunny days, respectively, on average in San Diego. The number of days in May and June that are "gloomy" varies from year to year. Anomalies in sea surface temperature can be used to forecast
4770-572: The warm core that fuels tropical systems. This value is well above 16.1 °C (60.9 °F), the long term global average surface temperature of the oceans. However, this requirement can be considered only a general baseline because it assumes that the ambient atmospheric environment surrounding an area of disturbed weather presents average conditions. Tropical cyclones have intensified when SSTs were slightly below this standard temperature. Tropical cyclones are known to form even when normal conditions are not met. For example, cooler air temperatures at
4876-411: The 500 hPa level, the air temperature averages −7 °C (18 °F) within the tropics, but air in the tropics is normally dry at this height, giving the air room to wet-bulb , or cool as it moistens, to a more favorable temperature that can then support convection. A wet-bulb temperature at 500 hPa in a tropical atmosphere of −13.2 °C (8.2 °F) is required to initiate convection if
4982-546: The Los Angeles Area are the major business districts of Downtown Pasadena , Downtown Burbank , Downtown Santa Monica , Downtown Glendale and Downtown Long Beach . Los Angeles proper has many business districts, such as Downtown LA and those lining Wilshire Boulevard , including Mid-Wilshire , the Miracle Mile , Downtown Beverly Hills , and Westwood ; others include Century City and Warner Center in
5088-399: The M w 6.7 1994 Northridge Earthquake and, to a lesser extent, the smaller M w 5.5 2008 Chino Hills earthquake . The Northridge earthquake occurred on a blind-thrust fault directly underneath the San Fernando Valley , which until the earthquake was previously undiscovered. Seismic retrofitting of existing and new construction is aimed to prevent damage and save lives in
5194-456: The Southern California desert system. Because of the barrier formed by the Tehachapi and Sierra Nevada ranges, cartographer George Wheeler observed in 1876 that Northern California was better connected to Oregon and Nevada than it was to Southern California. Following the acquisition of the territory of California by the United States, several pro-slavery politicians attempted to arrange
5300-493: The U.S., cattle and citrus were major industries until farmlands were turned into suburbs. Although military spending cutbacks have had an impact, aerospace continues to be a major factor. Southern California is home to many major business districts. Central business districts (CBD) include Downtown Los Angeles , Downtown Riverside , Downtown San Bernardino , downtown San Diego , and the South Coast Metro . Within
5406-432: The aftermath of a major quake, but it cannot guarantee that buildings will be unscathed if the epicenter is relatively close by. The 1994 Northridge earthquake was particularly destructive, causing a substantial number of deaths, injuries, and structural collapses. The quake caused the most property damage of any earthquake in U.S. history at an estimated $ 20 billion. Many Southern California faults are able to produce
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#17327796182185512-483: The beach. 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 500 to 2,000 metres (1,600 to 6,600 ft). These clouds begin to form when wind mixes moisture from
5618-690: The behavior of the Earth's atmosphere above, so their initialization into atmospheric models is important. While sea surface temperature is important for tropical cyclogenesis , it is also important in determining the formation of sea fog and sea breezes. Heat from underlying warmer waters can significantly modify an air mass over distances as short as 35 kilometres (22 mi) to 40 kilometres (25 mi). For example, southwest of Northern Hemisphere extratropical cyclones , curved cyclonic flow bringing cold air across relatively warm water bodies can lead to narrow lake-effect snow (or sea effect) bands. Those bands bring strong localized precipitation , often in
5724-555: The centers of their respective metropolitan areas, composed of numerous smaller cities and communities. The urban area is also host to an international San Diego–Tijuana metropolitan region, created by the urban area spilling over into Baja California . The main barrier to urbanization along the Interstate 5 corridor is Camp Pendleton . The cities and communities along Interstate 15 and Interstate 215 are so interrelated that Temecula and Murrieta have as much connection with
5830-612: The cities of San Bernardino and Riverside. In Orange County, has highly developed suburban business centers (also known as edge cities ) including the Anaheim–Santa Ana edge city along I-5; and another, the South Coast Plaza–John Wayne Airport edge city that stretches from the South Coast Metro to the Irvine Business Complex ; Newport Center ; and Irvine Spectrum . Downtown Santa Ana
5936-501: The cloudiest months in coastal California. June Gloom is stronger in years associated with a La Niña , and weaker or nonexistent in years with an El Niño . This weather pattern is relatively rare, and occurs only in a few other parts of the world where climates and conditions are similar. Scientists study the cloud fields that make up June Gloom to increase understanding of cloud behavior at the onset of precipitation. A typical June Gloom morning consists of marine stratus clouds covering
6042-551: The coast of southern California, extending a varying distance inland depending on the strength of the June Gloom effect that day. On a strong June Gloom day, the clouds and fog may cover the San Francisco Bay Area , penetrate far inland down valleys such as the Salinas Valley in central California , or extend into the Inland Empire of southern California. It's not uncommon for the layer to persist into
6148-408: The coast, but are only drawn inland during June Gloom events and related phenomena elsewhere in the world. Observations suggest that when marine stratus is present alone, drizzle is minimized. However, scientists believe that the presence of actinoform clouds within the marine stratus is indicative of an increase in drizzle and the onset of precipitation. Observation and computer modeling have shown that
6254-413: The cool air over the ocean, often develops on warm summer days as well, increasing the on-shore flow pattern and maintaining a constant flow of marine stratus clouds onto the coastal areas. A strong low pressure system passing over southern California will produce the deepest and most extensive June Gloom marine layer. The marine layer effect is weakened when a weak high pressure system is in place over
6360-500: The cool water of the California Current , and spread overnight into the coastal regions of California. The overcast skies often are accompanied by fog and drizzle , though usually not rain. June Gloom usually clears up between mid-morning and early afternoon, depending on the strength of the marine layer and the distance of the location from the Pacific Ocean , and gives way to sunny skies. May and June together are usually
6466-656: The daily and seasonal effects of Southern California's June Gloom are relatively rare. These include the western coast of Peru , the Macaronesian Islands , the western coasts of Morocco and Portugal , and Namibia in southern Africa. Researchers have discovered that the cloud fields forming June Gloom and related phenomena from other west-coast marine-influenced climates are excellent places to find and study actinoform clouds . These clouds have been found to be present more often than expected in common stratocumulus layers. These clouds are persistent year-round off
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#17327796182186572-594: The division of Alta California at 36 degrees, 30 minutes, the line of the Missouri Compromise . Instead, the passing of the Compromise of 1850 enabled California to be admitted to the Union as a free state , preventing the southern half of California from becoming its own separate slave state . Subsequently, Californians (dissatisfied with inequitable taxes and land laws) and pro-slavery Southerners in
6678-460: 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
6784-429: The first decade of the 21st century, droughts and wildfires have increased in frequency as a result of climate change . Southern California consists of one of the more varied collections of geologic, topographic, and natural ecosystem landscapes in a diversity outnumbering other major regions in the state and country. The region spans from Pacific Ocean islands , shorelines , beaches, and coastal plains , through
6890-749: The five most populous in the state, and are among the top 15 most populous counties in the United States. The motion picture , television and music industry are centered in the Los Angeles area in Southern California. Hollywood , a district of Los Angeles, gives its name to the American motion picture industry, which is synonymous with the neighborhood name. Headquartered in Southern California are The Walt Disney Company (which owns ABC ), Sony Pictures , Universal Pictures , MGM , Paramount Pictures , and Warner Bros . Universal, Warner Bros., and Sony also run major record companies. Southern California
6996-453: The form of snow , since large water bodies such as lakes efficiently store heat that results in significant temperature differences—larger than 13 °C (23 °F)—between the water surface and the air above. Because of this temperature difference, warmth and moisture are transported upward, condensing into vertically oriented clouds which produce snow showers. The temperature decrease with height and cloud depth are directly affected by both
7102-487: The furthest inland extent of the gloom, where the cloud deck is closest to the ground. By late morning to early afternoon, solar heating usually is sufficient to evaporate the clouds, and the sun emerges. The phenomenon forms earliest and lasts longest at the coast, with weaker effects as it moves further inland. When the marine layer is strong and deep, clouds can fill the Los Angeles Basin and spill over into
7208-584: The greatest rates of warming in the tropical Indian Ocean, western Pacific Ocean, and western boundary currents of the subtropical gyres . However, the eastern Pacific Ocean, subtropical North Atlantic Ocean, and Southern Ocean have warmed more slowly than the global average or have experienced cooling since the 1950s. Ocean currents , such as the Atlantic Multidecadal Oscillation , can affect sea surface temperatures over several decades. The Atlantic Multidecadal Oscillation (AMO)
7314-497: The immediate sea surface, general temperature measurements are accompanied by a reference to the specific depth of measurement. This is because of significant differences encountered between measurements made at different depths, especially during the daytime when low wind speed and high sunshine conditions may lead to the formation of a warm layer at the ocean's surface and strong vertical temperature gradients (a diurnal thermocline ). Sea surface temperature measurements are confined to
7420-404: The last 130 years due to the way they were taken. In the nineteenth century, measurements were taken in a bucket off a ship. However, there was a slight variation in temperature because of the differences in buckets. Samples were collected in either a wood or an uninsulated canvas bucket, but the canvas bucket cooled quicker than the wood bucket. The sudden change in temperature between 1940 and 1941
7526-430: The length and intensity of the June Gloom phenomenon in a given season. Years with warmer ocean temperatures, referred to as El Niño , may result in fewer gray days in May and June. Cooler ocean temperatures, associated with La Niña , usually foretell a more gray period. The climate charts below show a clear drop in the mean monthly sunshine hours and percent possible sunshine for the months of May and June, which are
7632-582: The lightly populated "cow counties" of Southern California attempted three times in the 1850s to achieve a separate statehood or territorial status separate from Northern California . The last attempt, the Pico Act of 1859, was passed by the California State Legislature and signed by State Governor John B. Weller . It was approved overwhelmingly by nearly 75 percent of voters to form the proposed Territory of Colorado . This territory
7738-505: The mid-afternoon or evening. The clouds, which are formed by the marine layer , move in at night, usually after midnight, and typically dissipate in the late morning, giving way to clear, sunny skies. During a heavy June Gloom season, the condition may persist into the afternoon, or even all day during an exceptionally strong event. Often, the air is saturated with moisture, and fog also develops, along with frequent light mist and occasional drizzle . Fog and drizzle normally are found near
7844-432: The mid-levels of the troposphere , roughly at the 500 hPa level, is normally a requirement for development. However, when dry air is found at the same height, temperatures at 500 hPa need to be even colder as dry atmospheres require a greater lapse rate for instability than moist atmospheres. At heights near the tropopause , the 30-year average temperature (as measured in the period encompassing 1961 through 1990)
7950-550: The more urban region) that have been left undeveloped. It is the third most populated megalopolis in the United States, after the Great Lakes megalopolis and the Northeast megalopolis . Much of Southern California is famous for its large, spread-out, suburban communities and use of automobiles and highways. The dominant areas are Los Angeles, Orange County , San Diego , and Riverside – San Bernardino , each of which are
8056-440: The ocean , approximately the top 0.01 mm or less, which may not represent the bulk temperature of the upper meter of ocean due primarily to effects of solar surface heating during the daytime, reflected radiation, as well as sensible heat loss and surface evaporation. All these factors make it somewhat difficult to compare satellite data to measurements from buoys or shipboard methods, complicating ground truth efforts. Secondly,
8162-410: 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
8268-631: The other line connecting San Bernardino, Riverside, and Orange counties directly. Southern California is also home to the Port of Los Angeles , the country's busiest commercial port; the adjacent Port of Long Beach , the country's second busiest container port; and the Port of San Diego . The following table shows all airports listed by the Federal Aviation Association (FAA) as a hub airport: Sea surface temperature Sea surface temperature (or ocean surface temperature )
8374-442: The region, and the marine layer will be very weak or nonexistent when there is a strong high-pressure system affecting southern California. The National Weather Service graphic on the right explains the effects of atmospheric conditions upon the marine layer and local weather conditions in more detail. While many parts of the world commonly have an offshore marine layer of stratus or stratocumulus clouds, other locations matching
8480-420: The satellite cannot look through clouds, creating a cool bias in satellite-derived SSTs within cloudy areas. However, passive microwave techniques can accurately measure SST and penetrate cloud cover. Within atmospheric sounder channels on weather satellites , which peak just above the ocean's surface, knowledge of the sea surface temperature is important to their calibration. Sea surface temperature affects
8586-494: The shape of the cloud fields actually rearrange themselves when the clouds start to rain. Southern California Southern California (commonly shortened to SoCal ) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California . It includes the Los Angeles metropolitan area (the second most populous urban agglomeration in the United States ) as well as
8692-471: The sole county to vote for the GOP, with Orange County having been Democrat since 2012. Southern California is one of the largest economies in the United States. It is dominated by, and heavily dependent upon, the abundance of petroleum, as opposed to other regions where automobiles are not nearly as dominant, due to the vast majority of transport that runs on this fuel. Southern California is famous for tourism and
8798-584: The southern section of the San Andreas (in the Palm Springs region, which has not ruptured in ~400 years), the entire Southern California portion of the San Andreas Fault is ready to produce a powerful earthquake in the near future. Notable faults capable of large magnitude events include the San Jacinto Fault (a splay of the San Andreas that runs directly under the I-10 & I-215 interchange),
8904-470: The state, formed by the northern boundaries of San Luis Obispo , Kern , and San Bernardino counties, which are not exactly a straight line. Another definition for Southern California uses Point Conception and the Tehachapi Mountains as the northern geographical barriers, especially when defining California's bioregions . In this definition, Owens Valley and Death Valley are part of
9010-491: 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
9116-518: The subpolar North Atlantic, the equatorial Pacific, and the Southern Ocean. The future global mean SST increase for the period 1995-2014 to 2081-2100 is 0.86°C under the most modest greenhouse gas emissions scenarios, and up to 2.89°C under the most severe emissions scenarios. There are a variety of techniques for measuring this parameter that can potentially yield different results because different things are actually being measured. Away from
9222-424: The surface layer denser and it mixes to great depth and then stratifies again in summer. This is why there is no simple single depth for ocean surface . The photic depth of the ocean is typically about 100 m and is related to this heated surface layer. It can be up to around 200 m deep in the open ocean . The sea surface temperature (SST) has a diurnal range , just like the Earth's atmosphere above, though to
9328-681: The surface temperature signature due to tropical cyclones . In general, an SST cooling is observed after the passing of a hurricane, primarily as the result of mixed layer deepening and surface heat losses. In the wake of several day long Saharan dust outbreaks across the adjacent northern Atlantic Ocean, sea surface temperatures are reduced 0.2 C to 0.4 C (0.3 to 0.7 F). Other sources of short-term SST fluctuation include extratropical cyclones , rapid influxes of glacial fresh water and concentrated phytoplankton blooms due to seasonal cycles or agricultural run-off. The tropical ocean has been warming faster than other regions since 1950, with
9434-417: The top eight largest cities in the United States. In Southern California, there are also 14 cities with more than 200,000 residents and 48 cities over 100,000 residents. Many of Southern California's most developed cities lie along or in close proximity to the coast, with the exception of San Bernardino and Riverside. Southern California has drifted left since 2004, and is solidly Democrat. Kern County remains
9540-534: The top portion of the ocean, known as the near-surface layer. The sea surface temperature was one of the first oceanographic variables to be measured. Benjamin Franklin suspended a mercury thermometer from a ship while travelling between the United States and Europe in his survey of the Gulf Stream in the late eighteenth century. SST was later measured by dipping a thermometer into a bucket of water that
9646-418: The two months when the June Gloom pattern is the strongest. June Gloom has been reported by some Californians to bring on symptoms consistent with seasonal affective disorder , although this is not well-supported by evidence. However, the normally-very-sunny Los 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
9752-498: The warm waters near the surface offshore, and replace them with cooler water from below in the process known as Ekman transport . This pattern generally increases nutrients for marine life in the region, and can have a profound effect in some regions where the bottom waters are particularly nutrient-rich. Offshore of river deltas , freshwater flows over the top of the denser seawater, which allows it to heat faster due to limited vertical mixing. Remotely sensed SST can be used to detect
9858-416: The water temperature and the large-scale environment. The stronger the temperature decrease with height, the taller the clouds get, and the greater the precipitation rate becomes. Ocean temperature of at least 26.5 °C (79.7 °F ) spanning through at minimum a 50- metre depth is one of the precursors needed to maintain a tropical cyclone (a type of mesocyclone ). These warm waters are needed to maintain
9964-405: The water temperature is 26.5 °C (79.7 °F), and this temperature requirement increases or decreases proportionally by 1 °C in the sea surface temperature for each 1 °C change at 500 hpa. Inside a cold cyclone , 500 hPa temperatures can fall as low as −30 °C (−22 °F), which can initiate convection even in the driest atmospheres. This also explains why moisture in
10070-483: The western Pacific Ocean. El Niño is defined by prolonged differences in Pacific Ocean surface temperatures when compared with the average value. The accepted definition is a warming or cooling of at least 0.5 °C (0.9 °F) averaged over the east-central tropical Pacific Ocean. Typically, this anomaly happens at irregular intervals of 2–7 years and lasts nine months to two years. The average period length
10176-730: The western Pacific and rainfall in the normally dry eastern Pacific. El Niño's warm rush of nutrient-poor tropical water, heated by its eastward passage in the Equatorial Current, replaces the cold, nutrient-rich surface water of the Humboldt Current . When El Niño conditions last for many months, extensive ocean warming and the reduction in Easterly Trade winds limits upwelling of cold nutrient-rich deep water and its economic impact to local fishing for an international market can be serious. Among scientists, there
10282-429: The world's busiest general aviation airport; major commercial airports at San Bernardino , Orange County , Bakersfield , Ontario , Burbank , and Long Beach ; and numerous smaller commercial and general aviation airports. Six of the seven lines of the commuter rail system, Metrolink , run out of Downtown Los Angeles, connecting Los Angeles, Ventura , San Bernardino, Riverside, Orange, and San Diego counties with
10388-435: The world's largest action sports events, including the X Games , Boost Mobile Pro , and the U.S. Open of Surfing , are held in Southern California. The region is also important to the world of yachting with premier events including the annual Transpacific Yacht Race , or Transpac , from Los Angeles to Hawaii. San Diego Yacht Club hosted the three America's Cup races from 1988 to 1995. The first modern-era triathlon
10494-592: The world's oceans. Warm sea surface temperatures can develop and strengthen cyclones over the ocean . Tropical cyclones can also cause a cool wake. This is due to turbulent mixing of the upper 30 metres (100 ft) of the ocean. Sea surface temperature changes during the day. This is like the air above it, but to a lesser degree. There is less variation in sea surface temperature on breezy days than on calm days. Coastal sea surface temperatures can cause offshore winds to generate upwelling , which can significantly cool or warm nearby landmasses, but shallower waters over
10600-528: Was grouped with other counties of the San Joaquin Valley , California's central agricultural valley. Southern California consists of a heavily developed urban environment, home to some of the largest urban areas in the state, along with the Deserts of California (part of which was even proposed to become a new county due to cultural, economic and geographic differences relative to the rest of
10706-603: Was held in San Diego's Mission Bay in 1974. Since then, Southern California, and San Diego in particular, have become a mecca for triathlon and multi-sport racing, products, and culture. Southern California has multiple sports franchises and networks, such as Fox Sports Net . Many of these locals and tourists frequent the Southern California coast for its beaches. Some of Southern California's most popular beaches are Malibu , Laguna Beach , La Jolla , Manhattan Beach , and Hermosa Beach . Southern California
10812-546: Was high in the Bakersfield-Kern County , Santa Maria , and San Luis Obispo areas. Most of Southern California has a Mediterranean -like climate, with warm and dry summers, mild and wet winters, where cool weather and freezing temperatures are rare. Southern California contains other types of climates, including semi-arid , desert and mountain , with infrequent rain and many sunny days. Summers are hot or warm, and dry, while winters are mild, and rainfall
10918-459: Was manually drawn from the sea surface. The first automated technique for determining SST was accomplished by measuring the temperature of water in the intake port of large ships, which was underway by 1963. These observations have a warm bias of around 0.6 °C (1 °F) due to the heat of the engine room. Fixed weather buoys measure the water temperature at a depth of 3 metres (9.8 ft). Measurements of SST have had inconsistencies over
11024-698: Was the name of a proposed new state which failed to get on the 2018 California ballot. The ballot measure proposed splitting the existing state into three parts. In December 2020, during the COVID-19 pandemic , the state government led by Governor Gavin Newsom divided the state into five regions for the purpose of issuing stay-at-home orders. The Southern California region consisted of the following counties: Imperial , Inyo , Los Angeles , Mono , Orange , Riverside , San Bernardino , San Diego , San Luis Obispo , Santa Barbara , and Ventura . However, Kern County
11130-475: Was the result of an undocumented change in procedure. The samples were taken near the engine intake because it was too dangerous to use lights to take measurements over the side of the ship at night. Many different drifting buoys exist around the world that vary in design, and the location of reliable temperature sensors varies. These measurements are beamed to satellites for automated and immediate data distribution. A large network of coastal buoys in U.S. waters
11236-773: Was to include a portion of the much larger Tulare County and all of San Luis Obispo County . The proposal was sent to Washington, D.C. , with a strong advocate in Senator Milton Latham . However, the secession crisis following the election of Abraham Lincoln in 1860 and the subsequent American Civil War led to the proposal never coming to a vote. In 1900, the Los Angeles Times defined Southern California as including "the seven counties of Los Angeles, San Bernardino, Orange, Riverside, San Diego, Ventura, and Santa Barbara." This definition left out San Luis Obispo and Kern counties. Southern California
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