Weather and Climate

Why does climate vary within the UK?

Winds- prevailing winds from the south west will bring warm and wet wind which makes the UK warm and wet, this means the west of the UK will get more of the warmth and rain than the east.
Latitude- How far north or south of the equator a place is. The higher in latitude a place is, the colder it gets. This is because the sun is at a lower angle in the sky, and so its heat energy is spread over more of the Earth's surface, so each place receives less heat energy.
Distance from the sea- Areas near the sea are warmer than inland areas during winter because the sea stores up heat and warms the land. Areas near the sea are cooler in summer because the sea takes longer to heat up than the Earth and so the land cools down.
Pressure- Low pressure weather systems have lots of rainfall because the air is rising and water vapour is condensing. High pressure weather systems have dry weather because the air is falling.
Altitude- The higher up you go, the cooler it is because the air is thinner so less heat energy gets trapped. Higher areas also get more rainfall because the air is forced upwards and the water vapour condenses to form rain

Depressions and Anticyclones:

Depressions are low pressure weather systems and anticyclones are high pressure weather systems- they cause different types of weather.

Formation of a depression:

Warm, moist air from the Tropics meets cold, dry air from the poles.
The warm air is less dense so rises over the cold air
Condensation occurs as the warm air rises and causes rain clouds to develop
Rising air also causes low pressure at the Earth's surface
So winds blow into the depression in a spiral
A warm front is at the front edge of the moving warm air and a cold front is at the edge of the moving cold air

Depressions cause a sequence of weather conditions, imagine you are stood on ground ahead of the warm front and the depression is moving towards you. When you are ahead of the warm front, there is no rain, high clouds, falling pressure, cool temperatures, increasing wind speeds. As warm front passes, there is heavy rainfall, low clouds, falling pressure, rising temperature, and strong winds. When the warm front is overhead, there is no rain, no clouds, a steady pressure, warm temperatures, and decreasing wind speeds. As the cold front passes there are heavy showers, thick clouds, rising pressures, falling temperatures, and strong winds. Lastly when the cold air is overhead, there are showers, high and broken clouds, rising pressure, cold temperatures, and a decreasing wind speed.

Anticyclones:

Anticyclones are where air is falling, creating high pressure and light winds blowing outwards
Falling air gets warmer so no clouds are formed, giving clear skies and no rain for days or even weeks
In summer, anticyclones cause long periods of hot, dry, and clear weather. The temperature is hotter because there are no clouds to absorb the sun's heat energy so more gets through to the Earth's surface and heats up the land
In winter, anticyclones cause long periods of cold, foggy weather. Heat is lost from the Earth's surface because there are no clouds to insulate the Earth's surface. The temperature drops and condensation occurs near the surface, forming fog.

Impacts of Extreme Weather

Floods can damage homes and possessions which can cost a lot to repair or replace
Businesses can be damaged by floods and people lose their income
Water use can be restricted during droughts
Increased rainfall may mean water supplies are increased
Droughts can cause crop failures
Increased rainfall can cause higher crop yields
A warmer climate means farmers can grow new crops, e.g. olives.
Flooding can cause death by drowning
Heat waves can cause death through heat stroke and heat exhaustion
Milder winters may reduce cold-related deaths

Climate Change

Climate change is any change in the weather over a long period of time. Global warming is the increase of global temperature over the last century. Global warming is a type of climate change and it causes other types of climate change, e.g. increased rainfall. There is a scientific consensus that global warming is caused by human activity such as burning of fossil fuels, farming, and deforestation has caused an increase in the concentration of carbon dioxide and methane in the atmosphere. These are greenhouse gases, this means that they trap heat reflected off the Earth's surface. Global warming can also be influenced by variations in solar output, the sun's output of energy is not always constant. When there is more energy coming from the sun, the Earth will heat up more. Lastly, changes in the Earth's orbit has an effect on global warming, the way the Earth orbits the sun changes, which affects how much of the Sun's energy the Earth will receive. If the Earth receives more energy, it'll get warmer.

Impacts of Global Climate Change

Global climate change will have economic, social, environmental, and political impacts on the world, and on the UK.

Economic Impacts:

Climate change will affect farming, in higher latitudes, farmers may be able to produce more output than usual. In lower latitudes, farmers' income may decrease because it's too hot and dry to farm properly

Climate change will also cause the weather to become more extreme, therefore more money will be spent on predicting these extreme weather conditions and events, reducing their impacts, and rebuilding after them

industries that help to reduce the effects of climate change will become bigger and make more money

Social Impacts:

Crop failure may lead to malnutrition and poor health and even death in poorer countries
More people will die due to extreme weather
Hotter weather will make it is easier for infectious disease to spread
Some areas will become uninhabitable

Environmental Impacts

Global warming is causing sea levels to rise, so some habitats will be lost as low lying coastal zones will be submerged
Rising temperatures and decreased rainfall may cause places to become deserts
The distribution of some species may change due to climate change.

Political Impacts

Water will become more scarce in some places and competition could result in conflict
Climate change may cause people to move and some countries may have to cope with emigration and immigration
Governments are under pressure to devise ways of slowing climate change and reducing the effects

Tropical Storms

Tropical storms are intense low pressure weather systems. These are huge storms with strong winds and torrential rain. Scientists are unsure of how exactly they are formed, but they are aware of where they form and some of the conditions required. Tropical storms develop above sea water that's 27 degrees Celsius or higher. They happen when sea temperatures are highest, so they happen at different times in different places. Warm, moist air rises and condensation occurs. This releases huge amounts of energy which results in the storms being really powerful. They move west because of the easterly winds near the equator. They lose strength as they move over land because the energy supply from the water is cut off.
Tropical storms are circular from above, and they spin anti-clockwise and move north westerly. They can be hundreds of km's wide, usually lasting between 7 and 14 days. The centre of the storm is called the eye and is caused by the air descending. There is very low pressure, light winds, no clouds, and no rain in the eye. The eye is surrounded by an eye wall, where there's spiralling, rising air, and very strong winds. Towards the edges of the storm, the wind speed falls, the clouds become smaller and more scattered, and the rain becomes less intense.

The primary impacts of a tropical storm are the immediate effects of strong winds, high rainfall and storm surges. The secondary impacts are the effects that happen later on as a result. Primary impacts may include buildings and homes being damaged, and a secondary impact as a result is people are left homeless. The impacts of tropical storms are more severe in poorer areas because, the houses are of poor quality, the infrastructure is poor, and poorer countries are often unprepared for natural disaster. However, people continue to live in areas where topical storms happen, this is because they have friends and family, and a job in the area, it also seems unlikely to people that it will happen again.

There are may ways of reducing the impacts of tropical storms, this requires prediction, planing, building techniques, education, and aid. Prediction means that when and where the topical storms will hit can be predicted using things such as radar, satellites and aircraft. This will provide time for people to prepare and evacuate, therefore reducing the number of injuries and deaths. Planning will involve ensuring future developments can be made to avoid the areas at most risk, emergency services can be provided and trained for, and governments can plan evacuation routes. Buildings can be designed to withstand the impacts of the tropical storms in the area, flood defences can be built, these will contribute to the prevention of a lot of damage as a result of tropical storms. Governments and other organisations can educate people about how to prepare and protect for tropical storms, people can also be taught how to prepare a survival kit containing things such as food and water and medication. Lastly, governments often send aid to countries affected by tropical storms. However, some strategies are more sustainable than others, for example, all of the methods above are effective, but some are more cost effective than others and therefore more sustainable.

Droughts:

Droughts are experienced when the weather conditions are far drier than usual, this is a long period when rainfall is below average. Water supplies become depleted during a drought because continue to use them when they are not being replenished by rainfall. Also, droughts are often accompanied by high temperatures which will increase the rate of evaporation, so water supplies are depleted faster. The length of a drought is different in different locations. Some of the climatic conditions required for a drought include when changes in atmospheric circulation mean it doesn't rain as much in an area for a long period of time. Droughts are also cause when high pressure weather systems (anti-cyclones) block depressions. Areas most at risk from drought are north-eastern Africa, the Sahel, southern Africa, the Middle East, Australia, and parts of eastern South America and Indonesia. People continue to live in areas affected by drought because they have always lived there, they have a job, and think it is unlikely to reoccur.

Similarly to tropical storms, droughts have primary and secondary impacts, for example, a primary impact includes vegetation dying, this causes the secondary impact of animals dying from starvation due to a lack of vegetation. Some human activities do increase the impact of droughts. This includes over-grazing, this will reduce the amount of vegetation in the area, making the soil erosion caused by droughts even worse, with fewer plants, soil isn't held together as strongly so it is eroded quicker. Excessive irrigation also worsens the effects of droughts. Irrigation is where water is artificially supplied from rivers and lakes to farmland areas in order to increase crop production. However, if this is done excessively, lake levels will deplete and less water is available. Also, when irrigation water evaporates, salts are left in the soil, this is called salinisation. Crops will fail to grow as well in salty water, further worsening the impacts of drought. Droughts are more severe in poorer areas, this is because these areas rely far more heavily on agriculture, and cannot continue to live as usual when there is a shortage of water, crops and soil will be ruined, livelihoods destroyed, and starvation can occur.

Fortunately, there are many ways to reduce the impacts of droughts. Prediction: this can be done through monitoring rainfall, soil moisture and river levels. When a drought is predicted, it allows strategies to be done to cope such as banning hose pipes and rationing water. Farming technique is also important, drought resistant crops can be grown and more effective methods of irrigation can be used, for example, drip irrigation which will deliver small volumes of water directly to the crop roots. These techniques reduce the demand on water supplies and make food production more reliable. Water conservation can be done by reducing the amount of water used at home, people can install features that specialise in using low levels of water. Increasing water supplies, for example, building reservoirs and wells can increase the supplies and make water more available when drought hits. Lastly, emergency aid can be sent in from other governments and organisations and can fund development projects.

	Created by charlottewilmot about 9 years ago

Note on Geography- Weather and Climate, created by charlottewilmot on 28/02/2015.