A kq2a: What is the pattern of air movement in the troposphere? Variations in global insolation

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A KQ2a: What is the pattern of air movement in the troposphere?

  1. Variations in global insolation.

-The tilt of the Earth's axis coupled with latitude controls the amount of insolation the Earth's surface receives. The higher the latitude the greater the seasonal variation of insolation.

-Maximum insolation is found in the tropical and subtropical deserts of the earth. Here, high sun angles and a lack of cloud cover in desert regions allow much solar radiation to the surface.

-Insolation decreases to a minimum at the poles where low sun angles and the fact that the Sun doesn't rise above the horizon nearly half the year reduces annual insolation.

-At the equator monthly insolation received at the top of the atmosphere varies between 390 and 415 Watts per square metre.

  1. Regions of high and low pressure. (The earth’s temperature and pressure distribution/seasonal variations.)

  • A region of low pressure or a low pressure system has lower pressure at its center than the surrounding areas. Winds blow towards the low pressure, and the air rises in the atmosphere where they meet. As the air is rising, water vapor within the air will condense, forming clouds and often precipitation as well. Because of the Earth’s spin/tilt and the Coriolis Effect, winds of a low pressure system spin counterclockwise north of the equator and clockwise south of the equator. There will typically be unfavorable weather that comes along with low pressure systems.

  • A region of high pressure or a high pressure system has higher pressure at its center than the surrounding areas. Wind blows away from the high pressure; winds of a high pressure system swirl in the opposite direction as a low pressure system. Air from higher in the atmosphere sinks down to fill the space left as air blew outward. Usually very good weather is associated with a high pressure system.

  1. Global and local wind systems.

Global Winds-

As the warmer air over the equator rises, colder air from the poles rushes toward the equator to take its place. This steady exchange of warm and cold air that occurs between the equator and the poles produces global wind belts. Global winds push air masses around Earth and bring changes in the weather. In the United States global winds called the prevailing westerlies push air masses from west to east.

Local Winds-

Small-scale convection currents arise from uneven heating on a smaller scale. This kind of heating occurs along a coast and in the mountains. Small-scale convection currents cause local winds. Local winds blow over a much smaller area and change direction and speed over a shorter period of time than global winds.

  1. The effects of land, relief and ocean currents.

-The sea affects the climate of a place. Coastal areas are cooler and wetter than inland areas. Clouds form when warm air from inland areas meets cool air from the sea. Ocean currents can increase or reduce temperatures. The Gulf Stream is a warm ocean current in the North Atlantic flowing from the Gulf of Mexico, northeast along the U.S coast and from there to the British Isles. Climate can be affected by mountains. Mountains receive more rainfall than low lying areas because as air is forced over the higher ground it cool causing moist air to condense and fall out as rainfall. The higher the place is above sea level the colder it will be.

  1. The location and characteristic features of the major climate regions to include (The study of climatic regions will be learned with the biomes included in the biosphere module.):

    1. Equatorial- Equatorial regions are located around the equator and cover about 6% of the Earth’s surface. They are often lowlands and have a hot and wet climate all year round. Tropical rainforests are located here. It is located 5 degrees North and South of the Equator. This region receives direct sunlight and lots of rainfall which makes the vegetation very thick and dense. The main areas are the Amazon region, Guinea Coast, Philippines, Malaysia, and Indonesia. These areas are often considered areas of high biodiversity and there are very specific species that only belong in these regions.

    2. Tropical Desert  - A tropical desert is the place of extremes. It is the driest & the hottest place on Earth. Rainfall is sporadic and in some years there is no measureable precipitation falls at all. The terribly  dry conditions of the deserts is due to the year-round influence of subtropical high pressure. The biggest Tropical Desert  is in northern Africa called the Sahara Desert. There are a few Deserts in the United States, such as the Mojave Desert, The Great Basin Desert

    3. Savanna- A savanna is a rolling grassland scattered with shrubs and isolated trees, which can be found between a tropical rainforest and desert biome. They can also overlap with other biomes. Not enough rain falls on a savanna to support forests. Savannas are also known as tropical grasslands. They experience a very dry season and then a very wet season. There are savanna's located in Africa, South America, India, and Australia.

    4. Monsoon- The tropical monsoon is most always located near the equator, so the monsoon experiences warm temperatures throughout the year. It’s climate ensures a tremendous amount of rainfall, tantamount to that of a tropical rainforest climate. A monsoon is a seasonal change in wind direction. The monsoon climate is generalized and characterized by seasonal variability of wind, humid summers, and dry winters. There are long amounts of time where there will be seemingly neverending rain. Following these long bouts of rainfall will be dry-spells that last for long as well. The monsoon only experiences the extremes of everything: with rain, there will be LOTS of rain; with heat will come scorching temperatures.

    5. Warm Temperate Climates- In geography, temperate or tepid latitudes of Earth lie between the tropics and the polar regions. The temperatures in these regions are generally relatively moderate, rather than extremely hot or cold, and the changes between summer and winter are also usually moderate. In certain areas, such as Asia and central North America, the variations between summer and winter can be extreme because these areas are far away from the sea, causing them to have a continental climate. In regions traditionally considered tropical, localities at high altitudes may have a temperate climate.

    6. Sub-Arctic- The subarctic climate also called subpolar climateor boreal climate is a climate characterised by long, usually very cold winters, and short, cool to mild summers. This type of climate offers some of the most extreme seasonal temperature variations found on the planet: in winter, temperatures can drop to −40 °C and in summer, the temperature may exceed 30 °C. However, the summers are short; no more than three months of the year (but at least one month) must have a 24-hour average temperature of at least 10 °C to fall into this category of climate. Deep in the interior of high latitude continents lies the subartic climate. Bitterly cold winters and mild summers result in the largest annual temperature range of any climate on Earth. The subartic climate is only found in the Northern Hemisphere because there is no large landmass at the same latitude in the Southern Hemisphere. Located in a large continental landmass between 50 to 70 degrees latitude the subartic climate is removed from any moderating influence of an ocean. It experiences a very large range in annual temperatures. The subartic climate is noted for its long cold winters, no wonder given that it is found in the source region for continental polar air masses.The subartic experiences the lowest temperatures outside of Antarctica and the largest annual temperature range of any climate.  

A KQ2b: How does it influence regional climates and local weather? (4 examples)

  1. The formation and characteristics of:

    1. Anticyclones (high pressure systems) - Anticyclones are areas of intense high pressure ranging above 1020mb. The air moves downwards towards the earth surface which compresses molecules. This causes the pressure to increase and become warm which makes the formation of clouds almost impossible. Anticyclones are around 3,000 kilometers wide and give several days of nice weather.

  • The UK experiences very long periods of stable weather because the anticyclones block the passage of the Polar Front Jet Stream.

  • During the Winter, anticyclones form over North America and Northern Caribbean.

  • The Siberian High lasts from September to April.

  • There are subtropical high pressure air masses over the south Atlantic and Pacific with their seasonal shifts.

    1. Temperate frontal depressions and tropical cyclones (hurricanes)- A hurricane, a type of cyclone, is a low-pressure system that typically develops in the tropics, including areas in the Atlantic, Pacific and Indian oceans. It often is accompanied by thunderstorms and, in the Northern Hemisphere, winds that churn counterclockwise near the Earth’s surface.

  • Hurricane Andrew was, at the time of its occurrence in August 1992, the most destructive hurricane in United States history

  • Hurricane Katrina was the eleventh named storm and fifth hurricane of the 2005 Atlantic hurricane season. It was the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States.

  • By the time storms make it across the Atlantic they are no longer getting their energy from the warm water, and they are similar to the winter storms that blow across the ocean. In 2009, Hurricane Bill crossed the Atlantic and hit the UK as a post-tropical storm. The leftovers of hurricanes Alberto, Gordon and Helene all hit the UK in 2006

  • On November 26, a cyclonic storm named Nisha rushed towards the coast of Tamil Nadu, India. More than 180 people were killed due to heavy rain and floods. Orathanadu village in Thanjavur District received over 990 mm of rain within a day. The total amount of rainfall during Nisha was about 1280 mm.

A KQ2c: What methods are employed to forecast weather patterns?

  1. Weather forecasting in relation to these weather conditions

-Surface pressure charts show the surface pressure pattern over a region using isobars (lines of equal pressure) and indicate areas of high (H) and low pressure (L) along with their central pressure value.

-Isobars are represented by solid lines.

-High pressure is usually associated with good weather (clear and sunny) while low pressure is normally associated with bad weather (rainy and cloudy). Fronts are also displayed.

-Where the isobars are close together, windy conditions may be expected.  Elongated areas of low pressure on surface and upper air weather maps are called "troughs" and elongated areas of high pressure are called "ridges.”

-A cold weather front is defined as the changeover region where a cold air mass is replacing a warmer air mass. Cold weather fronts usually move from northwest to southeast. The air behind a cold front is colder and drier than the air in front

-On a weather forecast map, a cold front is represented by a solid line with blue triangles along the front pointing towards the warmer air and in the direction of movement.

-A warm weather front is defined as the changeover region where a warm air mass is replacing a cold air mass. Warm fronts usually move from southwest to northeast and the air behind a warm front is warmer and moister than the air ahead of it. When a warm front passes, the air becomes noticeably warmer and more humid than it was before.

-On a weather forecast map, a warm front is represented by a solid line with red semicircles pointing towards the colder air and in the direction of movement.

  1. Traditional text based studies or student investigations. The use of weather charts, satellite data in forecasting and recording weather data (visual and infrared photography). 5 things

  • There are innumerable methods that help meteorologists forecast the weather patterns efficiently and accurately. Here are a few of the ways:

  1. Persistence Forecasting - a prediction that the weather in the future is going to be the same as it currently is; there will be no change in weather conditions. It is generally good but only for a short period of time and becomes less accurate as the amount of time enlarges.

  2. Trend Forecasting - The forecaster is looking at the changes that are occuring in the weather systems; the fronts, air masses, high and low pressure systems, etc. The forecast is based on the assumption that these changes will continue just as they have been occurring.

  3. Analogue Method - This technique states that existing weather patterns on weather charts which resemble previous weather patterns on previous weather charts should produce the same type of weather elements that the previous patterns produced.

  4. Climatological Forecast - This method uses such guidelines as the average value of weather elements for a region, the maximum and minimum values of weather elements, the most or least time of occurrence of certain weather phenomena, etc. to make a prediction of the value of those weather elements for some future period.

  5. Numerical Weather Prediction - Using mathematical equations which describe the processes occurring in the atmosphere that causes changes to weather elements; such as, temperature, pressure, wind speed and direction, moisture content, etc. These elements are used to describe the state of the atmosphere.

3. Relevant case studies to illustrate drought and hurricanes.

  1. At least 286 people were killed either directly or indirectly by Sandy. There were 147 direct deaths: 72 in the USA and the rest mainly in Caribbean, including 54 in Haiti and 11 in Cuba. In the USA of the 87 indirect deaths from Sandy, at least 50 were attributable to either falls by the elderly, carbon monoxide poisoning from inadequately ventilated generators and cooking equipment, or hypothermia as a cold snap followed Sandy and extended power outages left people without heating. Sandy was Cuba’s deadliest hurricane since 2005, whilst over the USA this was the greatest number of hurricane deaths from one storm outside of the southern states since Hurricane Agnes in 1972. Sandy was also the first hurricane to make landfall in Jamaica since 1988.

  2. The effects of Hurricane Ike in Texas were crippling and long-lasting. Ike's effects included deaths, widespread damage, and impacts to the price and availability of oil and gas. Hurricane Ike also had a long-term impact on the U.S. economy. Making landfall over Galveston, at 2:10 a.m. on September 13, 2008, "giant" Hurricane Ike caused extensive damage in Texas, with sustained winds of 110 mph, a 22 ft storm surge, and widespread coastal flooding.[More than 140,000 residents in the Texas Gulf Coast danger zones in Ike's path had failed to evacuate, partly due to fears of multi-hour traffic jams as during Hurricane Rita, but over 940 were rescued from rising waters, and nearly 2,000 rescued afterward. As of December 27, 2008, 37 people are known to have lost their lives in Texas due to Ike while hundreds are still missing.

  3. Drought is taking place as a heat wave extends across much of India with temperatures crossing 40C for days now. An 11-year-old girl died of heatstroke while collecting water from a village pump in the western Maharashtra state. THe girls’ death certificate says she died of heatstroke and dehydration.The pump she died at was a mere 500m from her house, but a typical wait for water stretches into hours. India is heavily dependant on monsoon rains, which have been poor for two years in a row. The government said that nearly 256 districts across India, home to nearly a quarter of the population were impacted by the drought. Schools have been shut in the eastern state of Orissa and more than 100 deaths due to heatstroke have been reported from across the country, including from the southern states of Telangana and Andhra Pradesh which saw more than 2,000 deaths last summer.

  4. An extreme drought in Syria between 2006 and 2009 was most likely due to climate change, and that the drought was a factor in the violent uprising that began there in 2011. The drought was the worst in the country in modern times, and in a study published Monday in Proceedings of the National Academy of Sciences, the scientists laid the blame for it on a century-long trend toward warmer and drier conditions in the Eastern Mediterranean, rather than on natural climate variability.

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