Biology

Biology

1. Formation of the atmosphere

2. Structure of the atmosphere

3. The atmospheric functions

Formation of the atmosphere

The atmosphere is a thin layer of gases that surrounds the Earth. Is made of a mixture of gases colled air. It is transparent and we cannot see it, unless there is wind or pollution. The Earth´s atmosphere started to form 4.600 billion years ago,when the planet was very young. Over billions of years, the atmosphere change its composition because of three main proces: - Big volcanic eruptions relased gases like nitrogen,water vapor, carbon dioxide (co2), methane, and ammonia. - The Earth solwly cooled, which caused water vapor to form clouds and heavy rain, creating the first oceans. - Simple acuatic organisms appeared in the oceans and started to do photosynthesis. Before life existed, the Earth´s primitive atmosphere was very similar to the atmospheres of Mars and Venus, made mostly of carbon dioxide and nitrogen. when living things that do photosynthesis appeared,they relased alot of oxygen and changed the atmosphere. The outer planets of the solar system (Jupiter, Saturn, Uranus, and Neptune) have very big atmospheres made mostly of hidrogen and helium. This is very different from the atmosphere of the inner planets (Venus, Earth, Mars, mercury) the inners planets are mainly formed of nitrogen and carbon dioxide.

2. Structure of the atmosphere

Thermosphere

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3.3. Temperature regulation

3.1. The atmosphere as a filter

3.2. Exchange of matter

The atosphere as a filter

The atmosphere filters solar radiartion: Some rays pass, others are blocked. -25% is absorbed by the ozone layer and inosthere, protecting life. -30% is reflaected by clouds and Earth´s surface ( albedo effect). -Only 45% rechaces Earths surface.

Exchange of matter

-Some gases, like nitrogen (N2) and carbon dioxide (CO2), came from volacnoes. -Other gases, like oxyegen (O2) and ozone (O3), were made by living beings, and they also protect life. -Most organisms need to exchange oxygen and carbon dioxide with the air . -Nitrogen is the most abundant gas and some solid bacteria fix it so plants can us it.

Temperature regulation

-Infrared radiation warms Earth´s surface and makes life possible. -This radiation does not reach all places equally: The equator gets more direct sunlight and is warmer than the poles. -Winds and ocean currents move heat from the ecuator to the poles. -Without this circulation, climates would be mach more extreme.

Layers of the Earth

Minerals

Mineral properties

Mineral classification

Rocks

A mineral is a solid, inorganic (they don´t come from living beings), natural substance, wiht a specific chemical composition (formed by the same atoms in the same proportion) and have a crystal structures so their particles are not organized,they are colled mineraloids. Ex: Obsidian

SHAPE:sometimes minerals can have geometric shapes, with flat faces with a geometric shape,like a cube, prisms, sheets,etc. They are called irregular shapes and never form crystals. COLOUR: The colour of the surface under white light.Some minerals are always the same colour. For example , sulphur is always yellow, emerald is green and ruby is red. However, many minerals are different colours because their composition can change sligthly or they can have impurities. In this case ,the mineral is said to have varieties. Ex:quartz can be colourless ( rock cristal), violet (amethyst),grey(smoked quartz), etc. LASTER: The way minerals reflect light. It can be: Metallic, like metals. HARDNESS: The resistence of minerals to be scratched. It is measured by using the mohs scale. This scale classifies the hardness of minerals from 1 ( the softest mineral) to 10 ( the hardest one) STREAK: The colour of the mineral in powder form. The mineral´s surface-colour can be different form its powder-colour. CLEARAGE: The way a mineral breaks up of cleaves. Ex: Mica cleaves into thin sheets, galena into small cubes, etc. If a mineral breaks down into irregular fragments , is called fracture. DENSITY D=M/V: The relationship between the mass and the volume of a substance. They can be lightor heavy. TASTE: Some minerals have a particular teaste. Ex: Halite has a salty teaste.ç MAGNETISM: Some minerals are attractedby magnets. Ex:Magnetite.

1) Silicates: They contain oxygen (O) and silickon (Si). They are the most diverse and abundant group. 2)Non silicates: They don´t contain silicon. They are lessa bundant but more heterogeneus (more veriety) than silicates. They are classified intogroups: Oxides : Magnetite Halides: Halite Carbonates: Aragonite Sulphates: Hypsus Sulphides: Pyrite Native elements (with only one typeof atom): Goldo ore cunnabar.

METAMORPHIC

Originated deep under the Earth’s crust and formed by changes (caused by pressure and temperature) in the composition of the minerals of preexisting rocks in a process called metamorphism. Can be foliated and non-foliated.

ORIGIN

Foliated: gneiss and slate. Non-foliated: quartzite and marble.

Examples

SEDIMENTARY

Originate from sediments that are fragments of other rocks that have beentransported and sedimented. Can be detrital (formed by remains of other rocks) or non-detrital (formed by remains of aquatic living things or mineral salts. They form strata and often have fossils.

ORIGIN

Foliated: gneiss and slate. Non-foliated: quartzite and marble.

Examples

MAGMATIC (IGNEOUS)

Originate when magma (melted materials and gases) cools down. Can be intrusive/plutonic (cool down slower inside the crust) orextrusive/volcanic (lava cools down quickly out of the crust).

ORIGIN

Extrusive rocks do not crystallize very well sothey have holes created by gases like pumice, basalt and obsidian. Intrusive rocks crystallize well like granite, diorite and syenite.

Examples