Investigation 4- Formation of Deserts
1. There are high-pressure and low-pressure belts on Earth because of the differences in area that include the location, the mountain ranges, and the coastal areas. It also has to do with the uneven warming of the sun because of the rotation of the earth on its axis. It also has to do with the air that is found around the equator, as it is uneven. This causes for heat to raise which in turn causes low pressure. Then, the air that moves out of these “lows,” toward the poles result in high pressure. High-pressure belts give rise to many of the world’s largest desert. This is because high pressure that is found in the upper atmosphere results in sinking air. Which in turn causes the air to be warm and dry and creates like a blockade that blocks air from below to rise and create clouds which creates rain. The warm air allows for more evaporation to take place, which causes for drier climate. Another factor contributing to this would be that there isn’t any strong winds either or moisture off large bodies of water that would help these desert areas, causing the land to be dry. Most large deserts are found at 30 degrees north and south of the equator.
a. The Eastern part of the state of Washington is located in the rain shadow of the Cascades. This area has dry climate with large areas of semiarid steppe along with arid plants. The amount of precipitation found on the east of the state differs from the west. The western side from the Olympic Peninsula receives much more rainfall than the eastern side, but the eastern areas receive more snowfall. In the state of Oregon, the high desert is located east of the Cascades. The Alvord Desert is dry and arid relative to the western part of Oregon. Annually, this region only gets about 15 inches of rainfall, but the Desert only gets about 7 inches a year. This desert was caused by the rain shadow of a mountain and not a range. The high desert can’t truly be characterized as being a desert as the region is more of a scrubland. The mountain that created this was the Steens Mountains. The Steens Mountain is the highest point in the high desert, it being 9,883 feet above sea level. It is considered by and from the high desert as being the basin and range of plate tectonics. b. The Desert that is located in all three states of Nevada, Utah, and Arizona is the Mojave Desert. It is an arid region that takes covers 25,000 square miles. It’s located between the Great Basin Desert and the Sonoran desert. Annually, it receives less than 13 inches of rainfall. This Desert is a rain shadow desert and is located on the dry area on the lee side of a mountain area. The mountain doing serves as a blockade as it blocks the area of rain producing weather system, and leaves behind a shadow. In turn, warm air is pulled by the prevailing winds found over the mountain. This causes for it to condense and then precipitate, and the dry air moves along leaving behind the rain shadow over and behind the mountain. During the summer, the Mojave desert suffer from extreme heat, and during the winter it cools off significantly. c. California’s Death Valley is the lowest, hottest, and most arid part of the North American continent. The rain shadow effect takes place in Death Valley, as air masses tend to lose moisture forcing it up the mountain ranges located in this area. It’s the driest part of America and receives about 1.5 inches of rainfall a year. When a lot of rain does come to this area it causes storms with flash floods. Because of the arid climate that exists causing for more evaporation to take place than precipitation, big amounts of salt are deposited in Death Valley. This causes for a lot of salt to add up on the basin floor that results in pans known as saltpans. d. The Atacama Desert of Chile is known as the driest place on earth, the average annual rainfall is 15 mm. It is also known as the driest non-polar desert in the world. The Atacama is probably the oldest desert on earth making it the longest continues arid region on the planet. The Atacama lies within the prevailing winds on the western side Andes. Being found at 20 degrees south, the common winds found is this area would be the moist air brought from the Atlantic. In turn, as the wind rises up across the Andes, it becomes cooler. The moisture in the air condenses which causes precipitation, meaning that this desert lies in rain shadow. The Monte Desert found on the Eastern side of the Andes differs from the Atacama Desert. This is because it is a warm “scrub” desert, and the climate is characterized as being temperate arid. Annually, this desert receives much more rain than the Atacama Desert, receiving about 80-250 mm. 4.
a. The east coast of Africa is more humid than the west coast because of the warmer water ability to evaporate faster than the cooler water, which allows making the air more humid and moist. The west coast is much more drier and is known to be a semi-desert. This is because the winds blowing on shore will be dry because of the cold ocean water. In addition, the east coast has the warm ocean current that flows south. The winds found in this area will be warmer and will be able to pick up more moisture and this will produce for precipitation to take place. b. The cold California Current contributes to the dryness of southern California, Arizona, and New Mexico because it keeps everything around dry. This is because the current brings upon low temperature, which means low humidity exists as well. The cold current allows for a more stable environment to exist off the coast of the Pacific Ocean.
5. There are several reasons why there is a large desert region in central Asia, while the central plains of the interior United States isn’t a desert. Compared to the United States, Asia is much a much larger piece of land. This is imperative because the center of large continents tends to be more extreme in temperature as well as drier. Because Central Asia has mountains, the Himalayas, and the other mountains of China and to the north, the moisture in the air doesn’t really have the potential to reach the area. This is because the Himalaya Mountains keep the weather from blowing into the central region. It works like a barrier keeping it out. Unlike Asia, the plains in North America are near and wide open to the Gulf of Mexico and the Pacific Ocean. This results in warm moist winds to have the ability to flow in to the plains. The direction of the wind and proximity to the warm water sources are great influences of the temperature found in a specific area.
a. Cloudy and rainy days is associated with low pressure. This is where strong areas of low pressure bring the stormiest weather. That is because it is an area of rising air. Low pressure is associated with rising motion. The rising air-cools and as it raises, it condenses and forms clouds and precipitation. The air then moves from high pressure to lower pressures, so if you have both high and low, it can be windy as the air pushes between the two pressures. b. The Earth’s major deserts are found at 30 degrees North and South. At these two locations, subsidence, sinking of an area, exists in the atmosphere. This means that as the air in a specific area sinks, it warms up as well because of the pressure that increases in the particular area, as you get closer to the ground. High pressure is associated with the sinking motions that lead to drier and warmer air. This is what causes clear, sunny skies and warm temperatures, with very little precipitation in an area. c. Rain shadow is a region that has little rainfall because it’s sheltered from prevailing winds by ranges of the hill. The rain shadows are caused when the moisture in the air is forced up a mountain and all the moisture is then all condensed out. Then when it reaches the other mountainside, the air is dry which causes the rain shadow. For example, when the low-pressure areas skirt the Rocky Mountains, it gives off high precipitation to the east side of the mountain but not the west side. d. Monsoons are seasonal changes in the direction of winds that usually bring about a change in local weather. Like most other winds found throughout earth, they occur in response to the sun’s task of heating the atmosphere around us. These are caused by differences in solar heating between the land (continents) and bodies of water (oceans). The low pressures found around the equator are simple convections that are due to the warm and high heat as well as the supply of humidity that is gathered from the oceans.
a. Plants-In the desert, plants have to be tough in order to survive during extreme heat temperatures. One-way is the succulence of plants, meaning that these plants store water in their roots, stems, and leaves. During short periods of time, like when it rains, plants gather as much water as they can and store it. Another way for these plants to survive is that they are thorny, spikey, spiny, or toxic. These adaptations help these plants survive as animals stay away from them. Animals want to eat these plants because they are food and they know that water is stored within them. These mechanisms allow for the desert plant to survive. A third strategy is their ability to be able to have a drought tolerance, this means that these plants are prepared for withstand long periods of extreme dryness. These plants are able to shed some of their leaves during this time allowing for the plant to not lose water because dropping the leaves in turn allows the water to conserve in the stems. Plants are smart and efficient in their survival skills in the desert. b. Vertebrate Animals- Vertebrate animals are animals that have a backbone or a skeleton; this would also include humans, as we are mammals. In the desert, vertebrate animals have many different strategies or adaptations to survive in the desert environments. For example, there are many animals who are nocturnal or crepuscular meaning that these animals are active at night. These animals use this “strategy,” because in the desert it is much cooler during the night. So, during the day instead of being out in the hot sun they instead hide away from the heat. Another strategy is when animals seek out cooler climates. Many animals try to avoid the surface temperature in deserts by creating their own “microclimates.” Animals will create their own microclimates by creating dens, nests, and burrows where they can cool off. The temperature in these certain places are much cooler than that of the desert surface. One major adaptation that many animals that live in the desert use to survive, like the camels and Gila monster, is that it stores fat. These animals store fat so that they can save it for tougher times when they are not able to find food. This is essential and a smart survival mechanism.
"Argentine Monte." Argentine Monte. N.p., 15 May 2014. Web. 26 Oct. 2014. <http://www.eoearth.org/view/article/150227/>. "Atacama Desert." Wikipedia. Wikimedia Foundation, n.d. Web. 26 Oct. 2014. <http://en.wikipedia.org/wiki/Atacama_Desert#Aridity>. Baker, Craig S. "20 Amazing Animal Adaptations for Living in the Desert." Mental Floss. N.p., n.d. Web. 19 Oct. 2014. <http://mentalfloss.com/article/57204/20-amazing-animal-adaptations-living-desert>. Briney, Amanda. "How Low and High Pressure Affects Global Weather." About. N.p., n.d. Web. 20 Oct. 2014. <http://geography.about.com/od/climate/a/highlowpressure.htm>. "California Current." Wikipedia. Wikimedia Foundation, 24 Oct. 2014. Web. 26 Oct. 2014. <http://en.wikipedia.org/wiki/California_Current>. "Climate of California." Wikipedia. Wikimedia Foundation, 24 Oct. 2014. Web. 26 Oct. 2014. <http://en.wikipedia.org/wiki/Climate_of_California>. "Death Valley National Park." Wikipedia. Wikimedia Foundation, n.d. Web. 26 Oct. 2014. <http://en.wikipedia.org/wiki/Death_Valley_National_Park#Climate>. "Desert Adaptations of Birds and Mammals." Desert Adaptations of Birds and Mammals. N.p., n.d. Web. 20 Oct. 2014. <https://www.desertmuseum.org/books/nhsd_adaptations_birds.php>. "Deserts Concepts." Deserts Concepts. N.p., n.d. Web. 26 Oct. 2014. <http://www.geologyclass.org/deserts_concepts.htm>. "Earth Science." Earth Science. N.p., n.d. Web. 25 Oct. 2014. <http://earthsciencesmsc.weebly.com>. "Geography of South Africa - Physical Geography - HowStuffWorks." HowStuffWorks. N.p., 15 Oct. 2009. Web. 26 Oct. 2014. <http://geography.howstuffworks.com/africa/geography-of-south-africa1.htm>. "High Desert (Oregon)." Wikipedia. Wikimedia Foundation, 23 Oct. 2014. Web. 24 Oct. 2014. <http://en.wikipedia.org/wiki/High_Desert_(Oregon)>. "How Plants Cope with the Desert Climate." Yecora Region. N.p., n.d. Web. 20 Oct. 2014. <http://www.desertmuseum.org/programs/succulents_adaptation.php>. "Mojave Desert." Wikipedia. Wikimedia Foundation, 24 Oct. 2014. Web. 26 Oct. 2014. <http://en.wikipedia.org/wiki/Mojave_Desert>. "Oregon." Wikipedia. Wikimedia Foundation, n.d. Web. 24 Oct. 2014. <http://en.wikipedia.org/wiki/Oregon#Climate>. Schowalter-Hay, Ethan. "All Types of Landforms in Death Valley." Travel Tips. N.p., n.d. Web. 26 Oct. 2014. <http://traveltips.usatoday.com/types-landforms-death-valley-104467.html>.
"Washington." Wikipedia. Wikimedia Foundation, n.d. Web. 24 Oct. 2014. <http://en.wikipedia.org/wiki/Washington_(state)#Rain_shadow_effects>. "Why is the Atacama Desert so dry?." BBC News. BBC, 28 Jan.