What is the atmosphere?
Earth’s atmosphere is a mixture of nitrogen, oxygen, water vapour, carbon dioxide, and several gases. The Atmosphere, the gas and aerosol envelope that extends from the ocean, land, and ice-covered surface of a planet outward into space.
The ozone layer protects the Earth from the Sun rays. The hole in the Ozone layer affects the life on Earth because UV rays impact on the Earth highly. Humans can suffer Skin cancer and other diseases, as well as the climate, is modified (speeding the Climatic Change) Global Warming.
- Burning fossil fuels increases the concentration of greenhouse gases in the atmosphere.
- The gases allow more of the sun’s rays to enter the atmosphere and absorb solar radiation when it is reflected back which traps heat.
- Global warming could melt the world’s ice caps and glaciers, causing an increase in sea levels and making many coastal areas uninhabitable.
- It could also affect weather patterns, causing droughts, flooding and hurricanes.
- To meet the increasing demand for energy without damaging the environment further; countries need to find new types of sustainable energy, industries need to use energy efficiently and people need to conserve energy.
Differences between weather and climate.
Weather is state of the atmosphere at a particular place during a short period of time. It involves such atmospheric phenomena as temperature, humidity, precipitation (type and amount), air pressure, wind, and cloud cover.
Climate is conditions of the atmosphere at a particular location over a long period of time. Not to be confused with the weather, climate represents Earth’s average conditions over time.
Climate Elements and Factors.
What factors affect the temperature? http://www.bbc.co.uk/bitesize/ks3/geography/physical_processes/weather_climate/revision/7/
Main climates factors: Temperature, precipitation, winds, atmospheric pressure and relative humidity (pg. 77-78)
Windward slope (Barlovento) Leeward slope (Sotavento)
In meteorology, leeward and windward are technical names for the directional sides of a mountain. The windward side is that side which faces the prevailing wind (upwind), whereas the leeward, or “lee” side, is the side sheltered from the wind by the mountain’s very elevation (downwind).
Windward and leeward aren’t just arbitrary terms, they are important weather and climate factors. One is responsible for enhancing precipitation in the vicinity of mountain ranges, and the other, for withholding it.
The climates can be summarised in:
- Cold climates: Highland, mountain, polar. Over 60º latitude N and S and high areas.
- Temperate or warm climates: Subtropical, cyclonic (oceanic, continental, etc), influenced by Water. Between 23.5 º and 60º Latitude N and S.
- Hot climates: Tropical and desert. Between the Equator and 23.5º N and S.
That three climates are different according to the latitude, altitude, proximity to water, etc.
The main climates in Spain are:
Continental, Mediterranean, Mediterranean-Continental, Alpine, Arid, and Oceanic (Atlantic)
Where can you locate every climate? Spain has, mainly, five different types of climate (Mediterranean-Continental is a variety inland).
- Continental in inland regions, far for the influence of the Sea. Some areas of Castilla-León and high areas, not mountainous. Cold winter and soft summer. Rainfall in winter and spring.
- Mediterranean. All the Arch on the Mediterranean coast. Affected by the sea, that temperate the climate. Temperatures are soft, warm winter and hot summer. Not much rainfall. In spring and autumn.
- Mediterranean-Continental. Inland. Not temperate. Cold winters and hot summers with no rainfall. Mostly all Spain, not on the coastline. Affected by the Mediterranean temperate, but with colder winters than in the Mediterranean and hot summers. High rate of temperatures between days and nights. Castilla La Mancha, Madrid, Aragón, Castilla- León, Extremadura.
- Oceanic. The Northmost part of the Iberian Peninsula. Humid and temperate. From Galicia to Pais Vasco. Higher rainfall and warm temperatures in Winter and Summer. Rate of temperatures not very wide.
- Alpine/Mountain. In the Pyrenees, Sistema Central, Sistema Ibérico, and Sistemas Béticos. Cold Winter, rainfall (snow) in Winter.
- Arid: In the Southwest of the Iberian Peninsula. Warm and dry. Little rainfall. Less than 100mm per year. Región de Murcia, Almería, South of Alicante.
Types of rainfall. (pg. 68-69 graphs)
Convection. In weather, it describes the vertical transport of heat and moisture in the atmosphere, usually from a warmer area (the surface) to a cooler one (aloft).
- Convectional rainfall
When the land warms up, it heats the air above it. This causes the air to expand and rise. As the air rises it cools and condenses. If this process continues then rain will fall. This type of rainfall is very common in tropical areas.
- Orographic rainfall
- Prevailing winds bring warm, moist air.
- Air is forced to rise over high areas.
- Air cools and condenses.
- Clouds form and it rains.
- Air descends on the other side of the mountains.
- It warms up and therefore becomes drier.
- When a cold polar air mass meets a warm tropical air mass they do not mix – they form fronts.
- The colder air mass is heavier than the warmer air mass, therefore the lighter, warmer air rises over the top of the heavier, colder air.
- As the warm air is forced to rise it cools. Also, the warm air is in contact with the cold air along the fronts, and this also cools.
- Condensation occurs and clouds form.
- Rain occurs along the front
5. Weather hazards
A weather hazard is an extreme weather event that threatens people or property. Weather hazards include:
Tropical storms are given different names in different parts of the world.
A tropical storm is a hazard that brings heavy rainfall, strong winds and other related hazards such as mudslides and floods.
Tropical storms usually form between approximately 5° and 30° latitude and move westward due to easterly winds. The Coriolis force sends them spinning towards the poles.
In most areas, tropical storms are given names. The names are alphabetical and alternate between male and female. This makes storms easier to identify, especially when they are close together.
It is hard to predict the path of a tropical storm, and therefore difficult to manage an adequate evacuation of an area if needed.
How do tropical storms form?
- Hurricanes need a lot of heat to form, which is why they usually occur over tropical seas (at least 26°C).
- The sun is close to the equator, providing energy to heat the ocean.
- The warm ocean heats the air above it causing it to rise rapidly.
- Water evaporates quickly from the hot surface of the ocean, so the rising air contains great amounts of water vapour.
- The rising air starts to spin (clockwise in the northern hemisphere)
- The centre of the storm – the eye – is calm.
- As the air rises it cools, condenses and forms towering cumulonimbus clouds.
- The rapidly rising air creates an area of intense low pressure. The low pressure sucks in air, causing very strong winds
- Once the storm moves over land it starts to lose energy and fades.
How a Hurricane is formed?
Case Study: Hurricane Katrina
Hurricane Katrina was a devastating storm that hit the area around New Orleans, USA, on 25 August 2005. It had social, economic and environmental impacts:
- 1,800 people died
- 300,000 homes were destroyed
- 3 million people were left with no electricity
- people had to move out of the area
- $300 billion of damage
- oil platforms were destroyed
- shops were looted
- fuel prices rose
- tourism decreased
- the storm surge flooded large areas of the coast
- 80% of New Orleans flooded as man-made levees, overwhelmed by extra water, broke
- cotton and sugar cane crops were destroyed
- delicate coastal habitats were destroyed
- tornadoes were created
https://en.wikipedia.org/wiki/Hurricane_Mitch (Mitch Hurricane, 1998)
Global warming over time.
http://www.bbc.co.uk/bitesize/ks3/geography/physical_processes/weather_climate/revision/7/ (Elements and factors)