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Tuesday, March 23, 2021

EL NINO - How warm Pacific Ocean temps can alter the weather where you live - Often blamed for any and all out-of-the-ordinary weather, El Niño is a naturally occurring climate event and the warm phase of the El Niño-Southern Oscillation (ENSO) during which sea surface temperatures in the eastern and equatorial Pacific Ocean are warmer than average. How much warmer? An increase of 0.5 C or more in average sea surface temperatures lasting 3 months in a row suggests the onset of an El Niño episode. El Niño means "the boy," or "male child," in Spanish and refers to Jesus, the Christ Child. It comes from South American sailors, who in the 1600s, observed the warming conditions off the Peruvian coast at Christmastime and named them after the Christ Child. El Niño conditions are caused by a weakening of the trade winds. Under normal circumstances, the trades drive surface waters towards the west; but when these die down, they allow the warmer waters of the western Pacific to seep eastward toward the Americas. A major El Niño event generally occurs every 3 to 7 years, and lasts for up to several months at a time. If El Niño conditions will appear, these should begin to form sometime in the late summer, between June and August. Once they arrive, conditions typically reach peak strength from December to April then, subside from May to July of the following year. Events are categorized as either neutral, weak, moderate, or strong.

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WEATHERING AND EROSION - Rock that is close to the land surface is subject to physical and chemical modification by a number of different weathering processes. These processes generally start with water percolating down into joints formed by stress release as the rock comes close to the surface, and are most intense at the surface and in the soil profile. Weathering is the breakdown and alteration of bedrock by mechanical and chemical processes that create a regolith (layer of loose material), which is then available for transport away from the site. Physical weathering are processes that break the solid rock into pieces and may separate the different minerals without involving any chemical reactions. Water entering cracks in rock expands upon freezing, forcing the cracks to widen; this process is also known as frost shattering and it is extremely effective in areas that regularly fluctuate around 0 degree Celsius, such as high mountains in temperate climates and in polar regions. Seawater or other water containing dissolved salts may also penetrate into cracks, especially in coastal areas. Upon evaporation of the water, salt crystals form and their growth generates localised, but significant, forces that can further open cracks in the rock. Changes in temperature probably play a role in the physical breakdown of rock. Rapid changes in temperature occur in some desert areas where the temperature can fluctuate by several tens of degrees Celsius between day and night.

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Sunday, March 21, 2021

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      Surge Tanks Function and Types of Surge Tanks By:  Syed Ahmad Amin Shah       Surge Tanks Definition Surge tank (or surge chamber) is ...
Friday, March 19, 2021

VERNAL POOLS - April showers bring May flowers – and vernal pools, if you live in California or Southern Oregon. Vernal pools are seasonal depressional wetlands that fill up with rainwater during winter and spring, but may be dry for part of the year. They are typically found on the West Coast, especially in California and Southern Oregon, but can also be found in parts of the Northeast and Midwest. Western vernal pools often occur within “vernal pool landscapes” where swales connect vernal pools to each other and to seasonal streams. Vernal pools vary in size from 1 square meter to more than 2 acres. Western vernal pools can connect to other pools and streams that flow seasonally or only after rain. Multiple studies show that California vernal pools fill with water and flow into these channels, sending water downstream during many days of the year. These connections can impact the base flow of downstream waters, altering their physical characteristics. Western vernal pools are also hot spots of biodiversity, with native plant and animal species some of which can only be found in vernal pool habitats. In a study of vernal pools, 17 out of 67 species were only found in one of the surveyed ponds. In turn, these plants and animals provide food and habitat for shorebirds and waterfowl. Vernal pools, like other depressional wetlands, can also help to store and slow floodwaters.

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