Category Science

          Desert regions experience very little rainfall, but flowers may still bloom after the rains come. Some flower seeds will survive in the desert soil for years, suddenly coming into bloom at the first sign of rain. These flowers will grow long enough to produce seeds, so that the cycle may continue.

          A desert bloom is a climatic phenomenon that occurs in various deserts around the world. The phenomenon consists of the blossoming of a wide variety of flowers during early-mid spring in years when rainfall is unusually high.

          The blossoming occurs when the unusual level of rainfall reach the seeds and bulbs that have been in a latent or dormant state and causes them to germinate and flower in early spring. It is accompanied by the proliferation of insects, birds and small species of lizards.

          In the Atacama Desert, a desert bloom occurs between the months of September and November in years when rainfall is unusually high. Normally, the Atacama Desert receives less than 12 mm (0.47 in) of rain a year.

          At its height, the phenomenon can be seen from just south of the city of Vallenar to just north of the city of Copiapo throughout the coastal valleys and Chilean Coast Range from September to November.

          Climatically, the event is related to the El Nino phenomenon, a band of anomalously warm ocean water temperatures that occasionally develops off the western coast of South America, which can lead to an increase in evaporation and therefore precipitation.

          The flowering desert is a popular tourist attraction with tourists visiting the phenomenon from various points around the southern Atacama, including Huasco, Vallenar, La Serena, Copiapo and Caldera.

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          An area that has experienced a very long period of hot, dry weather or drought may suffer a flood should heavy rain follow. This is because the soil will have become baked so hard and dry that the water produced by very heavy rainfall will not be able to drain away. This is sometimes called a flash flood.

          About one in five California residents now lives in a flood-prone area. The replacement value of buildings vulnerable to floods exceeds $575 billion. Climate change could increase these risks. Yet the amount we spend on flood management is currently just a fraction of state water spending.

          Now is the time to look at improving flood responses across the state, not when rivers are overflowing. If we’re serious about reducing flood damages, we will need to adopt an “all of the above” approach to managing flood risks. The palette of solutions includes reinforcing and improving structural protections such as levees and floodwalls, encouraging residents and businesses to buy flood insurance, utilizing green approaches like wetlands, and avoiding new development on the most flood-prone lands.

          The first line of defense—particularly for those in the so-called 100-year flood zone, which is prone to more frequent floods—has typically been levees. Our system of levees is in great need of improvement, and funds from a 2006 state bond have boosted investments to shore up these flood defenses. Yet we still have a large funding gap. We need to increase spending to protect our most vulnerable communities, while ensuring we get the biggest bang for our bucks with these investments. For example, setting back levees to allow rivers to have more room to flood can reduce flood damages, boost habitat benefits and even increase recharge to aquifers.

          While necessary in many places, structural systems are also the most costly and environmentally damaging elements of our flood-protection system. They’re also far from infallible, particularly in light of a changing climate. Flood insurance is an underutilized tool that complements structural protections, and can help people recover more quickly. Yet too few at-risk Californians carry flood insurance. State and local agencies must find new ways to promote greater adoption of insurance. One novel approach would give local or regional flood management agencies authority to buy insurance for the community. Pooling resources this way would increase coverage and cut costs. The legislature could encourage this by creating mechanisms to recover costs through assessments or fees.

          Finally, one of the best defenses against flooding is land-use planning and regulation that keeps people out of harm’s way. Many communities already discourage development in the most at-risk zones, but more needs to be done. The state doubled the protection standard for urban areas in the Central Valley in 2007. The state should consider using the higher standard major urban areas elsewhere in the state, which also face significant risk.

          There is only one certainty about California’s variable climate: the drought that is hitting the state today will, at some point, give way to floods. Strengthening flood management could have big pay-offs in protecting the public health and safety and the state’s economy.

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          A Drought occurs when there is less than 0.2mm (1/100in) of rainfall in an area over a period of about two weeks. Droughts are usually caused by an area of high pressure that remains in one place for a long period of time. This is called a blocking high. The blocking high will prevent the movement of low-pressure systems into an area, meaning that hot, dry weather will dominate that area, leading to a drought. Parts of Africa, Asia and Central America often experience periods of drought.

          A drought is a prolonged period with less-than-average amounts of rain or snow in a particular region. The severity of the drought depends on the amount of time that a region receives below-average precipitation.

          For example, a few weeks without rain could stress a farmer’s crops during the growing season. This is called a flash drought. But it could take a much longer dry period to see a full drought that would affect a region’s water supply.

          A drought is caused by drier than normal conditions that can eventually lead to water supply problems. Really hot temperatures can make a drought worse by causing moisture to evaporate from the soil. Just because a region is hot and dry doesn’t necessarily mean it is going through a drought. Droughts only occur when an area is abnormally dry. Here’s why:

          Rain and snow don’t fall evenly across Earth. Some regions are routinely wet and others are routinely dry. From season to season — and from year to year — the amount of rain or snow in a location can vary.

          However, over a period of many years, the average amount of precipitation in a region is fairly consistent. For example, in the deserts of the American Southwest, the average precipitation is less than 3 inches per year. But, the average yearly precipitation in Atlanta is about 50 inches.

          When a particular area gets less rain than usual, the soil gets much less moisture, too. The soil starts drying out and plants die. When this pattern continues for several weeks, months or years, the flow of streams and rivers decreases and water levels in lakes, reservoirs and wells fall. Eventually, the unusual dry weather causes water supply issues, and the dry period becomes a drought.

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          If less than 0.5mm (1/48in) of rain falls in an hour, it is described by meteorologists as light. When more than 4mm (1/6in) falls, the rain is described as heavy. The heaviest rainfall is experienced in the tropical and monsoon regions of the world. In other areas, periods of heavy rain rarely last longer than an hour.

          Concentrations of raindrops typically range from 100 to 1,000 per cubic m (3 to 30 per cubic foot); drizzle droplets usually are more numerous. Raindrops seldom have diameters larger than 4 mm, because as they increase in size they break up. The concentration generally decreases as diameters increase. Except when the rain is heavy, it does not reduce visibility as much as does drizzle. Meteorologists classify rain according to its rate of fall. The hourly rates relating to light, moderate, and heavy rain are, respectively, less than 2.5 mm, 2.8 to 7.6 mm, and more than 7.6 mm.

          Raindrops may form by the coalescence of small water droplets that collide or from the melting of snowflakes and other ice particles as they fall into warm air near the ground.

          Mount Waialeale, Hawaii, with a 20-year annual average of 11,700 mm (460 inches) from tropical easterlies, is the wettest known point on the Earth. The nearest competitor is Cherrapunji, Megh?laya, with an annual average of 11,430 mm from the moist tropical monsoon. Less than 250 mm and more than 1,500 mm per year represent approximate extremes of rainfall for all of the continents. Rainfall is slight in the central regions of the subtropical anticyclones, which are therefore the desert regions of the Earth. In parts of the desert no appreciable rain has ever been observed.

          Over most of Europe, South America, eastern North America, and central Africa, the annual rainfall exceeds 500 mm (20 inches), while over most of Asia, excluding India, Tibet, and China, the annual rainfall is less than 500 mm, being less than 250 mm in a long tongue extending from Arabia across to northeast Mongolia.

          The central regions of Australia, most of northern and a part of southwest Africa, portions of the intermontane area of the United States, and portions of the west-central coast and southern east coast of South America also have less than 250 mm of rain in the year. Portions of the western coast of Africa, between the Equator and 10° N, a strip of the western coast of India, parts of Assam, a coastal strip of Myanmar (Burma), windward mountain slopes in the temperate latitudes of North and South America, and many isolated tropical stations average more than 2,500 mm of rain in the year. Rainfall intensities greater than 30 mm in five minutes, 150 mm in one hour, or 500 mm per day are quite rare, but these intensities on occasion have been more than doubled for the respective durations.

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          Tropical areas experience a lot of rain because high temperatures cause a large amount of water to evaporate from the sea to make clouds. Coastal areas of the world tend to experience more rainfall than those inland. One side of a mountain range may be drier than the other, because the mountains block the winds that bring the rain. These and other factors account for the varying amounts of rainfall around the world.

          Changes in rainfall and other forms of precipitation will be one of the most critical factors determining the overall impact of climate change. Rainfall is much more difficult to predict than temperature but there are some statements that scientists can make with confidence about the future.

          A warmer atmosphere can hold more moisture, and globally water vapour increases by 7% for every degree centigrade of warming. How this will translate into changes in global precipitation is less clear cut but the total volume of precipitation is likely to increase by 1-2% per degree of warming.

          There’s evidence to show that regions that are already wet are likely to get wetter, but details on how much wetter and what impacts there will be on a local scale are more difficult to ascertain. The dry regions of the subtropics are likely to get drier and will shift towards the poles. For much of Europe, wetter winters are expected, but with drier summers over central and southern Europe.

          It is the changes in weather patterns that make predicting rainfall particularly difficult. While different climate models are in broad agreement about future warming on a global scale, when it comes to predicting how these changes will impact weather – and consequently rainfall – there is less agreement at a detailed level.

          It is likely that in a warmer climate heavy rainfall will increase and be produced by fewer more intense events. This could lead to longer dry spells and a higher risk of floods.

          So far, any impact that climate change may have had generally on regional rainfall cannot be distinguished from natural variations. However, for some specific cases a signal is starting to emerge. A recent study showed that man-made climate change substantially increased the odds of damaging floods occurring in England and Wales in autumn 2000. For the UK, current understanding suggests that increases in heavy rainfall during winter may start to become discernible more generally in the 2020s.

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          Umbrellas have been used for over 1000 years, and it is thought that they probably originated in China. Early umbrellas were made of paper and bamboo and waterproofed with varnish.

         We have seen evidence of umbrellas in the ancient art and artifacts of Egypt, Assyria, Greece, and China.

          These ancient umbrellas or parasols, were first designed to provide shade from the sun. The Chinese were the first to waterproof their umbrellas for use as rain protection. They waxed and lacquered their paper parasols in order to use them for rain.

          The word “umbrella” comes from the Latin root word “umbra”, meaning shade or shadow. Starting in the 16th century umbrella became popular to the western world, especially in the rainy weather of northern Europe. At first it was considered only an accessory suitable for women. Then the Persian traveler and writer, Jonas Hanway (1712-86), carried and used an umbrella publicly in England for thirty years, and he popularized umbrella use among men. English gentleman often referred to their umbrellas as a “Hanway.”

          The first all umbrella shop was called “James Smith and Sons“. The shop opened in 1830, and is still located at 53 New Oxford St., in London, England.

          The early European umbrellas were made of wood or whalebone and covered with alpaca or oiled canvas. The artisans made the curved handles for the umbrellas out of hard woods like ebony, and were well paid for their efforts.

          In 1852, Samuel Fox invented the steel ribbed umbrella design. Fox also founded the “English Steels Company“, and claimed to have invented the steel ribbed umbrella as a way of using up stocks of farthingale stays, steel stays used in women’s corsets. African-American, inventor, William C. Carter patented an umbrella stand on August the 8th, 1885. After that, compact collapsible umbrellas were the next major technical innovation in umbrella manufacture, over a century later.

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