KS3
Earth & Atmosphere
Earth’s atmosphere contains the oxygen that we need to breathe and plays an important part in protecting us from solar radiation.
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The structure of the Earth
The Earth’s Structure is a spherical shape.
It is made up of several key layers.
Core
The centre of the Earth is the core. It has 2 parts the inner core and the outer core.
Mantle
Then there is the mantle it is able to flow but has properties of a solid.
Crust
The crust is on the surface of the planet and is made of a thin rock which we live on.
The composition of the Earth explains the key chemicals that the Earth is made up of.
Olivine
The mineral Olivine is a Magnesium Iron Silicate and is yellow-green in colour.
Pyroxenes
Pyroxenes are a group of rock-forming minerals found in igneous and metamorphic rocks. They are generally dark green in colour.
Core
The core is mostly made of Iron and Nickel. There could also be some Oxygen, Silicon and Sulfur involved. The inner core is in a solid state, whereas the outer core is in a liquid state.
Mantle
The Earth's mantle is made up of two primary components. These are Olivines and Pyroxenes. The Earth's mantle is in a liquid state.
Crust
The crust is mainly made up of Oxygen, Silicon and Aluminium, with many other chemicals involved. The crust is in a solid state.
The rock cycle
There are three types of rocks in the rock cycle they are igneous, sedimentary and metamorphic. Rocks go through the rock cycle, where they go through different phases to become other rock types.
Three rock types
All three rock types have weathering and erosion occur, which changes them into sediment.
Sedimentary
Sandstone, limestone and shale are examples of sedimentary rock. Sediment loses water then, through cementation and compaction (pressure) the sediment becomes sedimentary rocks.
Metamorphic
Gneiss, slate and granite are examples of metamorphic rock. If heat and pressure are applied to igneous and sedimentary rocks, the rocks will become metamorphic rocks.
Igneous
Obsidian, basalt and pumice stones are examples of igneous rocks. When metamorphic and igneous rocks are melted, they become magma. When magma cools it becomes an igneous rock.
The carbon cycle
Carbon is naturally recycled all the time. The two ways carbon is released into the atmosphere are through the burning (combustion) of fossil fuels and through respiration. Both combustion and respiration produce Carbon dioxide (CO2).
Plants carry out photosynthesis. Through this process, Carbon dioxide is removed from the air. The Carbon is stored in plants inside molecules of glucose. Animals eat the plants transferring the Carbon.
Carbon dioxide
All living things die. The organisms that decompose matter release Carbon dioxide through respiration. Carbon compounds can become fossils under the right conditions and have a very long time to form.
The composition of the atmosphere
The atmosphere is made up of many types of gases. These gases are contained inside a shield called the ozone layer. The ozone layer is made up of molecules of oxygen found in the form of O3. Inside this ozone shield, there is an abundance of gases.
Oxygen
Oxygen (O2) the gas needed for us to breath, is the second most abundant gas. Oxygen makes up 21% of the atmosphere.
Nitrogen
Nitrogen (N2) has the highest abundance, making up 78% of the atmosphere.
Other gases
The remaining 1% is made up of all other gases. Of this 1%, the Noble gas Argon (Ar) is 0.9% and Carbon dioxide (CO2) is 0.04%. This leaves 0.06% for water (H2O) vapour (which varies depending on the part of the world) and all other gases.
Human activity and the impact on climate
Human activity has increased greenhouse gases on our planet. Greenhouse gases trap thermal energy (heat) from the Sun.
The greenhouse gases are Carbon dioxide (CO2), Methane (CH4), Ozone (O3), Nitrous Oxide (N2O) and water vapour (H2O). These gases occur naturally, but humans have increased the production of these gases. There are also synthetic gases produced by humans called Fluorinated gases.
The increased volume of these gases holding the heat in is called the greenhouse effect. How these gases stop the radiation by tangling up the longer infrared wavelengths, preventing the radiation from escaping the atmosphere.
Earth absorbs heat
The Earth naturally absorbs heat into the oceans, land and atmosphere, if this didn't happen the planet would be cold. A lot of the infrared radiation is meant to be emitted back out of the atmosphere, but the more we burn fuels and allow deforestation to occur the more greenhouse gases are formed and not removed.
The increased volume of these gases holding the heat in is called the greenhouse effect. How these gases stop the radiation is by tangling up the longer infrared wavelengths, stopping the radiation from escaping the atmosphere.
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