Geography of Southern California
The geography of Southern California is greatly influenced by the Transverse Ranges and the Peninsular Ranges; magnificent physical landscapes that have shaped Southern California and affected its development. Both ranges have their particular characteristics, from the trend of the mountains, to the different climates within each range. Climate can be examined in each of the ranges through the physical locations of the ranges. These two mountain ranges are a perfect example of the differences in climate found within California.
- Low Clouds & Fog 1.1
- June Gloom 1.2
Transverse Ranges 2
- Climate 2.1
- Geology 2.2
- Composite ranges 2.3
- Urban interaction 2.4
Peninsular Ranges 3
- Climate 3.1
There is a common belief that California is a place of sunshine and perfect weather, but while some parts of California do live up to this ideal, other areas have more extreme conditions. Around the coastal areas, the weather does not vary as dramatically as it does in the Inland areas. Climate is affected by factors such as latitude, topography, and proximity to water masses - primarily the Pacific Ocean, and Southern California's mountain ranges, especially the Transverse Ranges and the Peninsular Ranges are key players in the climate affecting this ideal.
Low Clouds & Fog
This is a general weather prediction for Southern California. Due to the topographic features and proximity to the Pacific, Southern California has its share of both low clouds and fog.
Coastal fogs are frequently generated by interaction between seasonal inversion layers and the coastal marine layer, and may reach as far inland as 20 miles, butting up against inland mountains or coastal mountain ranges. While Fog generally is the collection of water droplets or ice crystals suspended in the air at or near the Earth's surface, Southern California's fog varies from the light 'ground fogs' to a dense almost "Tule fog" (pronounced ˈtuːliː fog) in the Winter and Spring, depending on the interaction of cold air brought down from the local mountains and the warmer ocean air masses.
Sun-seekers know to avoid southern California beaches in the late spring. This period, known to the locals as June Gloom, dims the coastal skies of sunny southern California. During this time, the coastal clouds may remain all day, but often give way to some hazy afternoon sunshine. The number of gloomy days during this period vary from year to year. Years with warmer ocean temperatures, influenced by the broader El Niño weather pattern, may result in fewer gray days in June, whereas the cooler ocean temperatures associated with a La Niña pattern, usually foretell more gray days in the season.
The Transverse Ranges is a unique set of mountain ranges in California. They are the only mountain ranges that run west to east, as opposed to the rest of California’s ranges that run north to south. These mountain ranges run from Santa Barbara County into San Bernardino County. They derive the name Transverse Ranges due to their East-West orientation, making them transverse to the general North-South orientation of most of California's coastal mountain ranges.
The Transverse Ranges experience temperature differences from winter to summer of about 20 degrees Celsius. One factor contributing to this variability is the distance from the ocean: the eastern part of the Transverse Ranges is furthest from the coast and has the most drastic temperature variation, whereas the western part is closest to the ocean and therefore has less variance.
The amount of precipitation of any area is affected by elevation, and topography influences temperature within elevation ranges. The higher the elevation, the lower the temperatures, and with lower temperatures come increased precipitation. The highest point of the Ranges is San Bernardino Mountains at the eastern end of the Ranges. The southeastern part of the Transverse Ranges can be considered to have a desert climate. Mountain ranges can cause a rain shadow effect, when air flow inland from the ocean and it rises, it begins to cool and after it reaches the other side of the mountain it becomes warm and evaporates. This is one of the reasons for the dry conditions in the Transverse Ranges that are furthest from the coast. The Ranges are also affected by the Santa Ana winds, a regional wind system created when air is forced from a high pressure to a low pressure, causing air to move from inland towards the ocean. These dry winds usually originate at the eastern end of the Ranges.
The San Andreas Fault and many other faults run through the Transverse Ranges. Because of this, this area is one of the most geologically active regions in California, with surface changes from fractions of an inch to six feet. Sedimentary rocks from the late Mesozoic era and early Cenozoic era are found in the western part of the region. Near the eastern ranges, such as the San Bernardino Mountains, metamorphic rocks that resemble rocks of the Sierra Nevada can be found.
These east to west running ranges include a variety of different mountains. Some mountains are steep like the San Gabriel Mountains. Other areas of the Transverse Ranges have a very low elevation like the Mojave Desert. The mountains ranges comprising the Transverse ranges include:
- Santa Ynez Mountains
- San Rafael Mountains
- Sierra Madre Mountains
- Topatopa Mountains
- Santa Susana Mountains
- Simi Hills
- Chalk Hills
- Santa Monica Mountains
- San Gabriel Mountains
- San Rafael Hills
- Puente Hills
- San Jose Hills
- San Bernardino Mountains
- Little San Bernardino Mountains
- Tehachapi Mountains
- Sierra Pelona Mountains
- San Emigdio Mountains
People have taken full advantage of the Transverse Ranges. The Ranges create a number of coastal plans and valleys which have become densely populated because of their prime living conditions. Some of these valleys include: Oxnard Plain, San Fernando Valley, Simi Valley, San Gabriel Valley, and the Inland Valley. The mountain ranges create recreation and living areas and have several ski resorts and provide several hiking and off-road vehicle use areas. Many people reside in the hills of the Transverse Ranges, where they may work work locally or commute to work in more populated areas 'down the hill.' Such communities provide an alternative to city and suburban living in Southern California.
The Peninsular Ranges are a group of mountain ranges in the Pacific Coast Ranges, which stretch over 900 miles from southern California in the United States to the southern tip of Mexico's Baja California peninsula. They are part of the North American Coast Ranges that run along the Pacific coast from Alaska to Mexico. Elevations range from 500 ft to 11,500 ft (150 m to 3,500 m) and vegetation in these ranges varies from coastal sage scrub to chaparral, and from oak woodland to conifer forest.
The Peninsular ranges of Southern California include: the Santa Ana Mountains, San Jacinto Mountains, and the Laguna Mountains. The Peninsular ranges of Baja California include: the Sierra Juarez, Sierra San Pedro Martir, Sierra de la Giganta, and Sierra de la Laguna. These ranges run from north to south.
The Santa Ana Mountains are the largest natural landscape along the coast of Southern California. These mountains peak at about 5,689 feet. This range starts in the north, in the Chino Hills area heading southeast of the Puente Hills region.
The San Jacinto Mountains are located in the desert areas in the north and east side of Southern California. The San Jacinto Mountains peak at about 10,833 feet. They run from the San Bernardino Mountains southeast to the Santa Rosa Mountains. This mountain range is the northernmost part of the Peninsular Range.
The Santa Rosa Mountains are located at the southern end of the San Jacinto Mountains, where they connect to it. The range extends for approximately 30 miles (48 km) through Riverside, San Diego and Imperial counties, along the western side of the Coachella Valley, where they bound the Anza-Borrego portion of the Colorado Desert. The highest peak in the range is Toro Peak (8,716 feet).
The Laguna Mountains are located in the eastern part of San Diego County. They range northwest to southeast for approximately 20 miles and peak at Cuyapaipe Mountain (6,378 feet). These mountains extend northwest about 35 mi (56 km) from the Mexican border at the Sierra de Juárez. The Sonora desert lies to the east and the Santa Rosa Mountains are to the northwest.
The Sierra de Juárez are located south of the Laguna Mountains and north of the Sierra San Pedro Mártir, and west of the Sonora Desert. It shares the characteristic Mediterranean climate of the nearby Sierra de San Pedro Mártir, as well as similar flora and fauna.
The Sierra de San Pedro Mártir are located south of the Sierra de Juárez, and serve as the drainage divide for a portion of the peninsula, separating eastern drainage from western. The range hosts the highest peak in Baja California, Picacho del Diablo (10,157 ft). Like the Sierra de Juárez, it has the most Mediterranean climate of the Peninsular ranges.
The Sierra de la Giganta are located in the southern part of the ranges in Baja California. This mountain range is located on the northwestern part of Mexico and runs parallel to the gulf coast of the peninsula.
The Sierra de la Laguna are located at the southern end of the Peninsula Range, in the southernmost region of the Peninsula. The vegetation ranges from dry San Lucan xeric scrub near sea level, to pine-oak forests at the higher elevations.
As with the Transverse Ranges, areas along the coast tend to have less temperature variation than do inland areas. The Peninsular ranges also form a rain shadow on the Colorado Desert region of California and on much of the larger Sonora Desert. The ranges are affected by the marine layer that provides cooling temperatures and fog, and rainfall varies seasonally with tropical storm activity.