Meteorology Concepts, Hurricanes, Tornadoes, And Flooding Summary - Essay Example

of Institute Meteorology Concepts, Hurricanes, Tornadoes, and Flooding Summary A summary on natural disasters [Pick the HurricanesI. Background a. Hurricanes, Typhoons and Cyclones Hurricanes Typhoons and Cyclones are one of the most destructive elements of nature in as much that they have the potential to wipe out entire settlements spanning across cities and towns. The average hurricane has speeds up to 500 kilometers per hours strong enough to lift 20 pickup trucks and throw them 2 to 3 miles away. Hurricanes are caused due to atmospheric pressure imbalances and travel at great speeds forming a vortex that can rise up to kilometers in the air and span for miles together, engulfing and swallowing everything that comes in its way. Hurricanes are similar to twisters and tornadoes. They have similar circumstances in which give birth to them and are associated with similar geographic and climatic conditions. In the recent past many great Hurricanes have been known to cause immense damage to coastlines of various nations. The most prominent and notorious hurricane known to have wreaked havoc in the recent history of mankind id Hurricane Katrina that struck the western coast of north America devastating human settlement, leaving hundreds dead and homeless.(Prothero 276) The primary cause of a hurricane is a steep pressure gradient. If the pressure gradient of the immediate atmospheric layer over sea and land exceeds a certain level under the prevailing atmospheric conditions, it leads to the formation of a swirling vortex of warm and cool air layers or air streams that intertwine and start whirling at extremely high speeds. The warm air rises above making space for the heavier / denser and colder air to rush into the land mass. This happens at great dimensions near sea shores and coastal areas where the air temperature and pressure gradient exists for large volumes of air. The extreme pressure and temperature difference causes the triggering of a hurricane that gathers moisture and air mass as it travels towards the nearest coastal point. Due to lower air pressure near coastal areas during the day time, (because lands heats up and cools down faster than water due to lesser specific heat capacity), hurricanes rush into coastal stretches sweeping along and across their territories. The chief ingredients of hurricanes are warm water and warm air. As water starts evaporating, they rise up and gather in the atmosphere where they begin to condense. These water drops then start coagulating and form a cloud. The water droplets on condensation release heat and causing the moist cool air to rise up making way for more warm air. This cycle of warm air with water vapor rising and condensing to create low pressure continues, until it leads to the formation of a vortex above the sea. They become lethal only when they pickup solid masses like: tin sheds trees, construction equipment, concrete, metal and other solid chunks of masses lying open on the ground. This gives it that devastating strength and inertia to cause unthinkable damage to areas where it has swept across. Typhoons are also borne out of wind and water and due to climatic imbalances affecting coastal areas and causing large scale damage to human property and lives. A Typhoon is very similar to a hurricane and the circumstances under which a typhoon is created are the same as that of a hurricane. Several factors contribute to the formation of a typhoon. Hurricane and Typhoons are the major two natural threats that endanger life and human settlement in coastal areas. Apart from the Tsunami, which is a rather rare calamity and is linked with deep sea earthquakes, these two natural disasters pose a more immediate threat to life and property located along the coastlines of various nations. Factors which contribute to the birth of a Typhoon are similar to those of a hurricane, like warm water vapor, warm air above, the sea surface, atmospheric pressure above sea, temperature and pressure imbalances, steep temperature and pressure gradients etc. Cyclones are associated with the after effect of a thunderstorm. Torrential rain, thunderstorms, and inclement weather are the associated weather conditions that prevail during a cyclone. A cyclonic condition occurs when the local weather is rainy and stormy. Cyclones Typhoons and Hurricanes have common circumstances of origination and are consequences of similar weather patterns. Cyclones cause excessive damage to wired communication systems as for example, telephone networks, cable and wired internet networks, computer networks. They cause power breakdowns due to their sheer power in uprooting electric posts, heavy equipments, destruction of buildings and man-made constructions. A cyclone has the potential to travel for miles and affect large areas in cities and towns. b. A Perspective on Great Storms Unlike natural disasters that originate in land like, localized earthquakes, volcanic eruptions, forest fires and landslides, storms, typhoons, cyclones and hurricanes have an entirely different pattern of doing damage. It affects large areas of the land mass, bringing uniform devastation for hundreds of miles together, poses a direct threat to human lives and also claims the most number of human lives due to its easy accessibility to interior densely populated areas from coastal fringes. Some of the great storms that have affected human civilization have had its origins of the eastern coast of America and Latin-America. The temperature and pressure balances in the trans-Atlantic region are the major contributor to these storms. There were 20 tropical cyclones, 19 tropical storms, 7 hurricanes and 4 noteworthy hurricanes last year in the Atlantic region. (Prothero 321) Storms have always posed a direct threat to the existence and habitation of mankind especially in the coastal areas. The origin of storms being in the open sea, the worst affected have been coastal areas facing the sea shore. Some of the major storms in the recallable history of mankind are as follows. They have been mentioned here based on their magnitude and extent of damage. 1. Hurricane of July 1502 2. Tempest of 1609 3. Colonials Hurricane of 1635 4. 1667 – the year of hurricane (Mid Atlantic Region) Etc II. Hurricanes of 2005 Some of the noteworthy hurricanes of 2005 have been the most talked and researched on. Their origins have mainly been in the Atlantic region. Few of them also have had their origins in the West Atlantic Region. Some of the major hurricanes of the year 2005 are as follows: 1. Hurricane Katrina 2. Hurricane Rita 3. Hurricane Dennis 4. Hurricane Emily 5. Hurricane Stan 6. Hurricane Vince 7. Hurricane Wilma 8. Hurricane Alpha 9. Hurricane Beta 10. Hurricane Dean and, 11. Hurricane Felix Hurricane Katrina: Hurricane Katrina started out as a small, non threatening atmospheric unrest near the Caribbean region close to the Bahamas and manifested itself in the form of a tropical wave that emerged from the remnants of tropical depression that had been prevailing depression in the Caribbean region. At first it seemed to be local tropical wave that would eventually die down with time. With time its intensity only gradually grew. It soon emerged into the season’s eleventh name storm and 4th hurricane before making landfall in South Florida where it caused minimal destruction. A minimal hurricane in south Florida with maximum sustained speeds of 80 mph and gusts up to 95 mph it still appeared to be non threatening and one that would get diverted eventually. After crossing South Florida, Katrina emerged again near the South Eastern Gulf of Mexico and intensified to the 2005 season’s 3rd most devastating hurricane. It then reorganized into the most powerful and high magnitude storm in the Central Gulf region since Hurricane Camille and also 4th Category-5 hurricane in 3 years. Its highest recorded wind-speed was 174 mph and a minimum central pressure of 902 mb or 26.64 inches of Hg. It earned its place of the 4th most powerful hurricane of all times to hit the eastern coast of North America originating from the Atlantic region. It was behind Hurricane Gilbert (1980), Labor Day of Hurricane (1988) and hurricane Allen (1980). Areas in Buras, Louisiana were affected with 140 mph winds. Places near Bay St. Louis, Mississippi experienced hurricane Katrina with speeds up to 135 mph winds a 27 foot storm surge in Gulfport, Mississippi 22 foot storm surge in Bay St. Louis. Wind speed of upto90 mph was experienced as far east as Mobile, Alabama, which experienced its worst flooding in the last 90 years. A part of an oil rig broke away in Mobile Bay hitting a nearby causeway and causing extensive damage there. There were waves as high as 48 feet seen in the Gulf of Mexico. A total of 50 people were killed near the Mississippi region including 30 people who were staying in an apartment complex in Biloxi. The latest death toll is at 1,833 (Louisiana-1582, Mississippi-170, Florida-30, Alabama-48, Georgia-2, Tennessee-1).Net worth of damages estimates now are up to $81 billion. Estimates of monetary value of property loss make Katrina the costliest hurricane and natural disaster in United States History. (Prothero 353) III. Galveston, Oh Galveston! The Galveston was a powerful and devastating storm that played havoc in Texas in the year 1800 on 8th September. It is remembered even today due to the extent of damage the hurricane did and the lives it claimed IV. A Killer Named Nargis Tornadoes The Nargis Tornado originating from the Bay of Bengal and primarily affecting Burma and lower deltaic region of Bengal and Bangladesh is a very powerful storm. It has already claimed a whopping 22,000 lives and rendered 50,000 missing or homeless. I. Background a. Tornado Alley The name is synonymous with the region in United States, where Tornadoes are very frequent. Due to the geographical features of the zone near the eastern coast, close to the north Atlantic Coast, and also due to the prevailing climatic conditions it is a natural calamity prone zone. Much similar to the ring of fire in south Eastern Asia region notorious for a host of active volcanoes and fault zones triggering earthquakes, the Tornado Alley is famous for its tornado and storm conducive conditions. b. Kansas “Cyclones” Kansas Cyclones are one of the most devastating natural calamities to have struck Kansas State in the United State. Due to its central location, land locked from all sides, it is a collecting spot for small cyclones and tornadoes to accumulate and build up. As we know land cools and warms up faster than water due to its lower specific heat capacity. Whenever there is a depression at the coastal areas during the day time, the landward moisture laden air fills up the low pressure region, condenses, releases latent heat, thereby causing more warm air to accumulate. This causes the steady growth of potential storm triggering wind activity, which gradually moves across the “Tornado Alley”, picking u more surface material, moisture and gaining inertia. The optimum location of Kansas, right in the center of the land mass, a region where coastal storms land up with maximum force is the chief region for such devastating storms wreaking havoc on the places in and around this place. Generally Kansas Cyclones are extremely torrential in nature bringing rain and thunder storms along with it. It devastates homes, causes power break down due to damages to electricity, cable and communication lines. It does immense damage to property and claims hundreds of lives every year. c. What Causes Tornadoes The interaction of warm and moist air with cooler air currents towards the coastal areas causes Tornadoes. The causes of Tornadoes, Hurricanes and Typhoons are same and the circumstances under which they are formed or triggered are similar. Low pressure warm air currents and high pressure cool air stream interact in great volumes leading to a spiraling vortex that goes out of control and gathers mass, momentum and material transforming into a giant upright spinning whirlwind. d. Tornado Myths Tornadoes aren’t mystical or mythical in nature rather are simple outcomes or consequences of interaction of dissimilar weather patterns II. The Super Outbreak, 1974 As the name suggests, the Super Outbreak is the second largest tornado outbreak running close on the heels of 2011 Super Outbreak. It is recorded to be one of the most destructive tornadoes for a record period of non-stop activity for 24 hours at a stretch. From April 3rd to 4th , in the year 1974 were a total of 148 tornadoes out of which 30 were category F4/F5 tornadoes. It affected multiple states all of which were lying in the lane along which the tornado left its destructive trail of pandemonium and utter chaos. It was due a great depression that was building in the Central American region. A twofold cause, one of which was warm moisture laden air current flowing northward from the coastal regions in the South and other one being East-bound cool winds blowing from the Western colder parts of North America resulted in the deathly vortex that claimed 300 lives and caused unthinkable damage. III. Attach of the Killer Tornado, 1925 On the 28th of March 1925, one of the most lethal tornadoes in the history of natural disaster in the USA struck 5 mid western states. States dense in population, having a well established city architecture, manmade architecture and property of high value were in the damage trail of the tornado. It literally bisected North America, cutting through the five states affecting 3 Illinois states the most. The origin of the tornado was believed to be Ozark Mountains, from where it came out in the afternoon. It was one of the worst hours to hit, because of large number of people outdoor mainly due to school end timings, and prime working hours. The main path of the tornado was around 200 miles and it was believed to have travelled a total of 700 miles including all the deviations and detours from its original path. (Prothero 376) IV. Greenville The town of Greenville in Hunt County saw a powerful storm hit in the morning hours. Major structural damages were done to commercial and residential establishments. Roofs were ripped off, electricity posts were flung across streets, communication lines snapped and civic architectures heavily damaged. Flooding I. Background a. Floods, Mythic and Real Floods have been associated with mankind and the journey of human civilization from early ages to the present day of high technology and advanced water harvesting techniques. The fact that has remained unchanged and common in all the major floods in the history of mankind affect different cities, locations and countries is the helplessness of human capabilities against the raw force and sheer wrath of nature. The worst form of disaster that can damage crops and claim human lives apart from other effects like damage to structures etc is flood. It has mainly caused immense damages in cities located close to rivers, coast lines and inland water bodies. On a realistic perspective Floods occur due to primarily one major cause, which is excessive rainfall. At times its effects and onset are catalyzed due to improper drainage system, yielding of flood gates or dam walls, land-slides or coastal erosion etc. One of the most recent floods in the year 2007 had affect coastal city of Mumbai in India claiming thousands of lives and spreading epidemics. Floods also expose mankind to various air borne and water borne diseases along with destruction of crops, food products etc. b. Flooding in a Flash Flash Floods occur within a few hours and cause enough destruction and chaos in places that are affected the most. They are short term events occurring within 6 hours of the causing element, heavy rain, dam failure, rapid melting snow and ice jams. II. The Great Scablands Floods The Scabland Floods the massive and intensive floods that created the channels of Scabland. The massive floods swept across eastern Washington and downwards to the Columbia River Plateau. Due to this periodic and incessant sweeping of floods it lead to the creation of Channeled Scablands formed by rectangular cross-sections spread over immense areas in eastern Washington. III. Los Angeles River Flooding A widely studied and epic river flooding in the year 1938 occurred in the city of Los Angeles. The flood of 1938 had a significant impact on the geographic identity of the California region. It was responsible for much of the inundation of Los Angeles, Orange and Riverside Counties in California during early 1938. It caused destruction of roads, bridges and buildings stranding hundreds of people. It also claimed 100 – 150 people one of the worst tragedies to have ever hit the area. Blizzards, Heat Waves and Climate Changes I. Background a. What Causes Blizzards? Blizzards are cols dry winds that blow at great speeds in the higher latitudes, near arctic and Antarctic regions. Blizzards coincide with heavy snowfall and hazardous high altitude weather. They represent one of the most dangerous weather conditions in higher altitudes and upper latitude regions. Blizzards or snow storms along with Avalanche are the two most prominent threats to human settlements in upper North America, North Western Canada, Greenland, Central and Northern Iceland, Northern Russia etc. b. Cretaceous Park Winter blizzards are common in Cretaceous Park c. The “Super-Interglacial” Greenhouse The super interglacial greenhouse is going to be another green house effect after 10,000 years. The predicted end of our current inter glacial is around 10,000 years from now. There have been interglacial cycles in the last 150,000 years the previous one ended 125,000 years ago. II. The “Great Blizzards” of the 1880’s The great blizzards of the 1800’s were one of the worst blizzards in the United States’ recorded history. The two main blizzards were in the year 1888 and 1889.New York, New Jersey, Massachusetts and Connecticut were affected the most with 10 – 50 inches of snowfall. It brought entire cities to a standstill with rail-roads blocked, and people forced to stay indoors for weeks. Public transit was paralyzed and normal life severely affected. III. The “Storm of the Century,” 1993 The Storm of the Century in 1993 had drastic effects on the people of United States. More than 2.5 million people were powerless. This storm is sometimes referred to as the Super storm and at times referred to as the storm of the century. The convergence of three independent weather patterns in the gulf of Mexico in March 1993 resulted in three days of bone chilling cold, numerous storms, biting cold, tornadoes and blizzards. Around 33 million acre feet of snow and rain fell during that period. IV. Brave New Greenhouse World Meteorology Concepts I. The Atmosphere a. Thermal Layering This is a property of the atmosphere by which excess and unbearable heat is cut out from the earth’s surface due to the heat repelling particles in the earth’s atmospheric envelope. The Mesosphere/ Ionosphere acts as the main layer responsible for the heat repelling mechanism, cutting out dangerous rays and excess heat. b. Layers of the Atmosphere 1. Troposphere a. Lowest layer of the atmosphere, and the one we live in. Troposphere s the lower most layer containing breathable air with 23 % oxygen, 70 % nitrogen and the remaining percentage of other gases and inert gaseous substances. It is the layer with the most atmospheric activity involving precipitation, rainfall, storms, thunder etc. It ranges from sea level to 10 km up into the atmosphere. b. Only layer with vertical and horizontal movement of the air. It is the only layer with physical movement of its gaseous contents i.e., air. Air moved vertically due to the process of convection where warm air displaces cold dense air and cold air settles beneath warmer and rarefied air. Air moves horizontally in the form of wind currents and lateral pressure differences, high altitude air turbulence due to movement of clouds, thunder storms, mid air storms and other variations in temperature and pressure. c. Precipitation The phenomena of precipitation cause the formation of clouds due to the coagulation of water droplets and coalescing of water particles to form heavier and liquefied water masses in the form of rain bearing clouds. The troposphere being nearest to the earth’s surface and having the right mix of gases facilitate the process of precipitation leading to the Water Cycle which maintains equilibrium of water availability in the form of ground water, river water and inland stored waters (e.g. dams, lakes, reservoirs etc). d. Tropopause The upper limit at which the Troposphere ends and the Stratosphere begins stand for the Tropopause. It demarcates the end of the Troposhpere and beginning of the Stratosphere. 2. Stratosphere a. Layered, three layers. The Stratosphere is the second layer of the atmospheric layers. It ranges from 10 km to 30 km. b. Ozone in this layer blocks UV rays, serves as the Earth’s sunscreen. The ozone layer in this layer consists of ozone molecules that react with UV light to produce oxygen molecules. In other words it acts as a protective shield against the harmful UV radiation (high frequency radiation) coming from the sun by making it react in its layer and countering its harmful effects. c. Stratopause The Stratopause is the point that marks the end of the Stratosphere and the beginning of the Mesosphere. It serves as the line of demarcation where the stratosphere ends and the mesosphere begins. 3. Mesosphere a. “Middle Layer” The mesosphere layer of the atmosphere consists of ions or charged particles. These particles act as excellent heat repellents or thermal insulators blocking away lethal and excess heat from the sun as well as harmful high frequency radiation. It ranges from 50 km to 90 km. Mesosphere b. Radiates heat back out to space. It’s very constituents of charged particles act as good heat reflectors. They form a heat shield reflecting direct heat and warm frequencies from the sun c. Mesopause Mesopause marks the ends of the Mesosphere and beginning of the thermosphere which is the last layer of the atmospheric layers. 4. Thermosphere a. Uppermost portion of the atmosphere. It forms the uppermost portion of the atmosphere and merges with the outer space. It is farthest from the surface of the earth. It starts at 90 km from earth’s surface. b. Warms at the top by friction between the atmosphere and solar winds The upper fringes of the thermosphere warm up due to constant solar wind currents blowing over the layer. This leads to friction which causes generation of heat, c. No distinct upper boundary, grades up into space. It diffuses into outer space and has no upper boundary. II. The Hydrologic Cycle a. Earth’s water purification system. The natural water purification system is quite a fascinating one wherein water travels from various sources in various forms and states from its origin through various stages back to its source. Water’s prime source is considered to be melting glaciers and thick frozen ice found on mountains. These glacier’s and large ice masses melt giving rise to streams, which in turn grow to become rapids and rivulets. There further at lower plains and basins converge with other tributaries and small streams to form rivers. The water on earth’s surface and in the sea evaporates and precipitates in the atmosphere, specifically in the lower troposphere regions. Rain bearing clouds feed these rivers and replenish ground water which is used and again fed back into the sea. Thus the cycle of water fed in and out to and from the water bodies consist the hydrological cycle. b. Transfers heat between the ocean and atmosphere. The heat from the ocean is transferred to the atmosphere through evaporation of warm water in the form of water vapor in the atmosphere. The warm moist water cools down into heavier water droplets releasing its latent heat and causing the air to warm up further. The transfer of heat from the ocean to atmosphere is the reason for cyclones, typhoons and sea storms. c. Cycle 1. Evaporation Water evaporates from local and ocean water bodies due to heat. 2. Condensation It condenses as it rises above and reaches the cooler regions of the atmosphere. 3. Precipitation Water vapour precipitates and coagulates to form heavier droplets of water 4. Ice and Snow Ice and Snow melts to form river sources 5. Runoff Water runs off various sources into sea or underneath the ground to collect as ground water 6. Infiltration and Groundwater Water seeps beneath the earth’s surface to collect as ground water. III. Weather and Climate a. Weather 1. Conditions of the moment. Weather consists of the present, real-time or present conditions of rainfall, humidity, temperature, visibility, fog, sunlight, wind, pressure etc. It represents the more immediate and instantaneous local conditions of natural atmospheric conditions reported through meteorological studies and forecast. 2. Includes such information as temperature, pressure, cloud cover, precipitation, wind speed and direction. It includes information on the temperature (highest, lowest, and average), pressure (instantaneous pressure), humidity, wind speed and direction, fog conditions and visibility, illumination due to sunlight, suspended particulate matter, changes of rainfall etc. b. Climate 1. Average of the conditions in a region. Climate represents a general and a more weather average condition spaced out in time 2. General, not specific. It is general to a place and is not local or region specific. 3. Seasonal Climates changes according to the season and the time of the year. It has a direct dependency on the season. IV. Air Pressure and Storms a. What is Pressure? Pressure is the effect felt of air mass or gaseous mass on a certain body. In scientific terms or as per the definition in physics, Pressure is the force exerted by any substance in unit area of its containing surface or surrounding surface. It is felt whenever there is a gaseous or liquid mass contained in a bound volume. 1. General air pressure is the weight of the air above a point on the Earth’s surface. Air pressure measured in atm (Atmospheres) or in bars is the pressure exerted by the column of air on unit meter square of surface area on the earth’s surface. It differs from region to region depending on the proximity of the surface to the sea surface or sea level. 2. At sea level, the weight is 14.7 pounds per square inch, or 1 atmosphere. Unit air pressure i.e., 1 atm is the value of atmospheric pressure on a unit area of surface at sea level. 3. When the air rises up into the Troposphere or falls towards the Earth’s surface, the can influence the air pressure. The movement of air across the different atmospheric layers of the earth can drastically affect the atmospheric pressure. As air moves from the lower Troposphere to the higher Stratosphere or Mesosphere, the density of air decreases and air becomes more rarified. This results in a rop in air pressure. The opposite, i.e., movement of air from higher layers to lower layers causes a steep increase of air pressure. 4. When the air rises up from the Earth’s surface, it “pulls” on the surface air and creates an area of low pressure. When air rises up due to its lesser relative density or lesser specific density, it leads to low air pressure. Lesser air, lesser density would mean lesser air pressure. 5. When the air sinks towards the surface, it presses down and creates high pressure. Sinking air would cause more mass of air converging at the same point , leading to an increase in air pressure. b. High Pressure 1. High, or higher than normal pressure. High Pressure stands for an atmospheric pressure greater than the natural/ ambient atmospheric pressure. 2. High pressure generally indicates clear skies and sunshine. High Pressure areas act as the source of inter land mass or intra land mass air flow. It acts as the source of air currents to low pressures. High pressure regions exhibit clear skies, sunny weather and calm and pleasant weather. c. Low Pressure 1. Low, or lower than normal pressure. Low pressure is the pressure that is lower than atmospheric pressure or ambient pressure. 2. Low pressure generally indicates cloudy skies and precipitation. 3. Includes tornadoes and hurricanes. V. Fronts a. Air Masses 1. Large parcels of air that develop a condition dependent upon the region in which they form. Air masses are large chunks or envelopes of air that display a certain density, humidity, density and pressure. In other words air masses demonstrate different fluid properties. 2. They are characterized by moisture and temperature. Air Masses are segregated or characterized by moisture and temperature. Air temperature changes causes same or similar air temperature masses too cling on to one another and move together as one current. 3. Continental (dry) and Maritime (moist), Tropical (warm), Polar (cold) and Arctic (very cold). Air masses differ depending on the region on the surface of the earth where they are found. Such air masses exhibit characteristics like humidity, salinity, dryness, suspended particulate matter (spm content), etc. continental air masses are characterized by their dry and saline feel. Maritime air is cold and moisture bearing. Tropical air is warm and at times warm and moist together. Polar and Arctic regions show cold conditions. 5. When they move, the front of the air mass forms a front Air in transit forms a pattern and a front. b. Fronts 1. Warm Fronts a. Occurs when warm air replaces cold air at the surface. This is a natural atmospheric phenomenon that tales place when warm rising air steadily moves outwards replacing cold air. 2. Cold Fronts a. Occurs when cold air replaces warm air at the surface. The reverse of it can also be found where cold air replaces warm air at the surface or at the bottom, closer to cooler land mass at night and near the sea surface during the day. 3. Stationary Fronts a. Eventually, air masses lose their “steam” and stop moving. As air masses move they lose their thermal and molecular energy. As a result they become stationary b. At that time, the boundary becomes stationary. A stationary air mass represents a stationary boundary when it loses it kinetic and thermal energy, c. The air mass will either dissipate, or can reverse direction. The mass of air will either diffuse into other air masses or can also reverse its direction of transit. 4. Troughs a. A place in the atmosphere where the air pressure drops. It is a place in the atmosphere where the air pressure reaches its minimum. It is an extremely low pressure region or zone in the atmosphere. b. At times, these troughs can be places where clouds form, but there may be no precipitation. There may be instances where clouds might accumulate or be found in such troughs but they may not be rain bearing clouds. References 1. Prothero, D. R. “Catastrophes! Earthquakes, Tsunamis, Tornadoes, and Other Earth-Shattering Disasters”. Johns Hopkins University Press. 1 Jan 2011. Web 20 Apr 2011. Read More