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WEARTHER HAZARDS AND CLIMATE CHANEG - Coggle Diagram
WEARTHER HAZARDS AND CLIMATE CHANEG
STRUCTURE OF THE ATMOSPHERE
4 Layers: troposphere, stratosphere, mesosphere and thermosphere
The troposphere is the lowest layer of the atmosphere. This is the layer where we live and where weather happens. Temperature in this layer generally decreases with height. The boundary between the stratosphere and the troposphere is called the tropopause. The jet stream sits at this level and it marks the highest point that weather can occur.
learn the hadley, ferel and polar cells on the diagram (page 10 of notes)
1) High pressure - brings good weather, no clouds, no rain
2) Low pressure - brings clouds and rain
3) High pressure is sinking air
4) Low pressure is rising air
Hottest deserts of the world are found 30 degrees north and south of the equator. This is because all the cool dense air rises at the equator, it reaches the tropopause. This causes air to part in both directions. Once this reaches around 30 degrees north and south the air is hot and sinks, causing the hottest deserts. As the air goes in again it gets cooler. This is called the hadley cell (at 30 degrees is high pressure, no clouds or rain)
The UK is cloudy and wet because it is on the edge if the ferrel cell and the polar cell. This means is has permanent low pressure. If there is low pressure, it means it will bring clouds and rain. As the UK is also an island, the wind can collect large amounts of moisture, releasing it in the low pressure zones where the UK is.
At the equator, it is hot and wet all year round – this creates a humid. climate. The annual rainfall close rainfallWater droplets that fall from clouds. is high as it rains almost every day. The temperatures are constant all year round – the temperature range is usually only a few degrees.
Taking the Hadley cell, warm air at the equator (0° of latitude) rises and then cools in the upper atmosphere, then circles back down towards the tropics (i.e. 30° of latitude). The air in the Ferrell cell moves in the opposite direction to the air in the Hadley cell with warm air moving toward the polar regions.
1) Sinking air forms areas of high pressure. Surface winds move outwards from these areas. 2) Rising air forms areas of low pressure. Surface winds move towards these areas of low pressure. 3) Surface winds are distorted by the Earths rotation - known as the Coriolis effect. 4) The patterns of pressure belts and winds are affected by seasonal migration of the thermal equator
Jet steams
Polar front jet stream - this is formed when cold polar air meets warm tropical air high above the Atlantic Ocean. This normally occurs between latitudes 40 and 60 degrees North and 40 and 60 degrees South. However, the exact location does vary. What is key is that this occurs at the division between the Polar and the Farrel cells.
The Subtropical jet stream - this is also generally in a westerly direction. It can be found at approximately 25 degrees North and 35 degrees South.
CHECK PAGE 13
Milankovitch Cycle
Eccentricity - Earth encounters more variation in the energy that is receives from the sun when the Earths orbit is elongated than it does when Earth's orbit is more circular.
Tilt - The tilt of the Earth's axis varies between 22.2 and 24.5 degrees. The greater the tilt angle is, the more solar energy the poles receive.
Precession - A gradual change, or 'wobble' in the orientation of Earth's axis affects the relationship between Earth's tilt and eccentricity.
The amount of energy that the Earth receives from the sun is not constant. Sometimes the Earth receives more energy and sometimes less. These changes are very small and hard to detect but are connected to the idea of sunspots. A sunspot is a dark patch on the surface of the sun. The number of sunspots increases from a minimum to a maximum, then back down again over a period of about 11 years. This 11-year period is called a sunspot cycle. When sunspot activity is at a maximum the sun gives off more heat (about 0.1%). When sunspot activity is at a minimum the solar output is reduced, which can lead to lower temperatures on Earth.
There was a reduction in sunspot activity between 1645 and 1715 which corresponded with the Little Ice Age (a cooler period).
Sunspot activity has been increasing since the 1940's which could explain some of the rise in global temperatures.
Volcanoes
Large volcanic eruptions release ash and Sulphur dioxide into the atmosphere
The ash particles return quickly to earth but the sulphur dioxide can have a cooling affect.
The eruption needs to be violent