Global atmospheric circulation Tropical storms Global atmospheric circulation The atmosphere is the air above our heads on which we depend for life. Atmospheric circulation involves a number of interconnected circular air movements called cells. Sinking air create high pressure and rising air creates low pressure. Surface winds move from high to low pressure, transferring heat and moisture from one area to another. These winds curve due to the Earth’s rotation and change seasonally as the tilt and rotation of the Earth causes relative changes in the position of the overhead sun. formation Rising air draws evaporated water vapour up from the ocean surface which cools and condenses to form huge towering clouds. The condensing released heat which powers the storm and draws up more water vapour. Many thunderstorms join to form a rotating storm. Storms spins at 75mph with an eye at the centre. Winds blow the system and it gathers strength. On land the storm weakens. Global atmospheric circulation drives the world’s weather. Cloudy and wet in the UK because 60 degrees north is close to where cold polar air from the north meets warm subtropical air from the south. Hot and dry in the deserts as this is where air is sinking which means little rain. Hot and humid at the Equator due to low pressure and sun overhead, so hot humid air rises bringing heavy rain to the rainforests. What is a tropical storm? Tropical storms are huge storms called hurricanes, cyclones and typhoons in different parts of the world. They form 5-15 degrees north and south of the Equator. They occur in summer and autumn when ocean temperatures are 27c or above. The spinning effect (Coriolis) effects of the Earth’s rotation is very high. Intense humidity and heat makes the air unstable.

Tropical storms may become more intense. Structure and features of tropical storms Typhoon Haiyan November 2013 Category 5 that hit the Philippines Primary Effects Secondary Effects 6300 killed- most in storm surge. Over 600000 displaced. 40000 homes destroyed or damaged. 90% of Tacloban destroyed. 30000 fishing boats destroyed. 14 million affected. 6 million jobs lost. Flooding caused landslides which blocked roads. Shortages of water, food, shelter and power leading to diseases  Looting in Tacloban Immediate Responses Long-term Responses Rapid overseas aid included NGOs. US helicopters assisted rescues. Field hospitals set up. 1200 evacuation centres set up. UN and international financial aid, supplies and medical help. Rebuilding of infrastructure. Oxfam replaced some of the fishing boats More cyclone shelters built. There is evidence that global warming exists and this may impact on the distribution, frequency and intensity of tropical storms. Over the last few decades sea surface temperatures in the tropics have increased by ¼ to ½ a degree. Tropical storms may become more intense. In the Atlantic 6 out of the 10 most active years since 1950 have happened since the 1990s. 2004 saw Hurricane Catarina hit SE Brazil. The area has never had a hurricane before this. However there is no clear evidence and more data needs to be collected over a longer period of time.

Reducing the effects of tropical storms Weather hazards in the UK Protection- methods of protection involve buildings with reinforced concrete, shutters on windows, built off the floor to reduce the effects of storm surges. In Bangladesh they use the shelters at other times for community centres. Weather hazards in the UK In the UK there are occasional extreme weathers such as: Heatwave that hit in 2003 that killed 2000 people. Heavy snowfall in 2010 which closed schools temperatures in Bolton reached -17c Weather is the day to day conditions of the atmosphere whereas climate is the average weather taken over 30 years. Somerset Levels floods 2014 Causes Immediate responses SW depressions brought record rainfall in Jan and Feb. High tides and storm surges swept water up the rivers from Bristol channel. Rivers not dredged for 20 years. Media took a big interest. Cut-off villages used boats for transport. Community groups provided valuable support. SEE impacts Long-term Responses Over 600 homes flooded. Schools closed. £10 million damages. Power cuts, roads and rail cut off. £20 million Flood Action Plan launched by the council and Environmental Agency to reduce the risk of future floods. River Tone dredged. Road levels raised. Planning- education and media campaigns raises awareness for individuals and communities and enables people to prepare to reduce the effects. Monitoring and prediction-LICs with limited technology use bikes with sirens on to warn people to prepare of an approaching storm. HICs have technology such as satellites which track the paths.

Climate change- evidence and natural causes Human causes of Natural effects of greenhouse gases: Greenhouse effect keeps the Earth naturally warm to support life. Without average temps would be at about -18c. Global temperatures have been cooling gradually over 5.5 million years, but increasing in recent decades. Many consider contemporary global warming to indicate climate change. Land glaciers melting is adding water to seas and oceans. Thermal expansion, so the warmer oceans expand in volume. Climate change is having a significant effect on global ecosystems and on people’s lives. Human impact: Carbon dioxide is most important, contributing approximately 60% to warming by greenhouse gases. This comes from burning fossil fuels in industry and power stations. Transport and agriculture also contribute. Deforestation of tropical rainforests is also a large contributor. Methane emissions from agriculture (cows), rice farming, sewage treatments and emissions from landfill sites is growing even faster than carbon dioxide. Natural causes Orbital changes-Milankovitch cycles Eccentricity: every 100,000 years the orbit changes from circular to elliptical (oval) and back again. Axial tilt: every 41,000 years the tilt of the Earth moves back and forth between 21.5 degrees to 24.5 degrees. Precession or wobble: over 26,000 years the axis wobbles from one extreme to the other. Natural causes Solar activity: sunspots on the surface of the sun mark short term reduction in surface temperatures. They are usually followed by explosive, high-energy solar flares increasing heat output. Volcanic activity: Eruptions of ash can block out the sun causing reducing of temperature but only for a short period. Sulphur dioxide erupts out which is converted in sulphuric acid which acts like mirrors reflecting the heat back into space.

Managing Climate Change Managing climate change Carbon Capture Not yet economically viable (too expensive). It uses technology to capture carbon dioxide produced by industry and power stations then compressing and piping it to underground storage areas. Alternative energy Burning fossil fuels accounts for 87% of all carbon dioxide emissions. Solar, wind, Hydroelectric Power (HEP) reduce greenhouse gases. UK wants to produce 15% of it energy using renewable sources by 2020. Managing climate change Agriculture adaption Particularly in low attitudes farmers will have to: Use efficient irrigation systems. Grow more drought resistant crops. Plant trees to shade seedlings from the strong sunlight. International Agreements This is a global issue and needs governments working together. The Paris Agreement of 2015 was the first legally binding global climate deal. It aims to limit global temperature increase to 1.5c above pre-industrial levels. Planting trees Trees remove carbon dioxide from the atmosphere through photosynthesis. They also release moisture which produce clouds, this reduces solar radiation coming in. Reducing risk from rising sea levels: Since 1900 sea levels have risen by 20cm. By 2100 this could increase to an increase of 1m rise. This will cause challenges such as: Threatening agriculture land in places like Bangladesh. Increase coastal erosion. Countries like the Maldives will be lost. The Maldives are now constructing a sea wall of 3m around the capital Male and sandbags used elsewhere. Houses are being built on stilts. Plans made to move the entire population to Sri Lanka or India. Global impacts of climate change Reduces crop yields and water supplies. More heat related illnesses and diseases such as malaria. More extreme weather. Changes to ecosystems.