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Volcano

Definition:

Volcanoes have different shapes and forms. Some look like mountains (cone like shape) from which molten rocks and gas can erupt. In simple words, it is an opening through the Earth crust.
When a volcano in not in eruption, everything is happening inside it. But what is going on in there?

Volcanoes are formed when hot liquid, molten rocks and gas, known as magma is forced to the surface of the earth by natural forces such as temperature and pressure. During this process the land around the column of magma rises to form the shape of the volcano
Most of the volcanoes are situated close to the tectonic plates boundaries. But they can appear other places too.

How Does It Work?

The Layers
Illustration of the different layers of the planet Earth.

Our loved planet Earth is not solid everywhere! And volcanoes are proof of it. As you can see on the illustration, we live on a the outer part of the planet called the crust. It is about 35 kilometers thick and the thinnest layer. Deeper within the Earth and surrounding the planet's core is a liquid layer called the outer core. The mantle (composed of the upper and lower mantle) sometimes produces the magma that flows out of the volcanoes as lava.

The Movements
Illustration of a volcano with tectonic plates.

The crust is not one solid piece. In fact if it were, we might not have any volcanoes! Indeed the crust (composed of the oceanic crust and continental crust) moves with the tectonic plates.
The tectonic plates form the lithosphere. They are huge section of rocks that are constantly moving. Where those plates meet the friction creates a lot of energy with very hight temperature and pressure. Cracks form and the magma can emerged from a magma chamber producing a volcano.
Although volcanoes are mostly found at the contact of two tectonic plates, they are also found away from those plates boundaries in hotspots zones. Hotspots are formed when very hot magma makes its way through the crust. They happen when magma is especially hot and the conditions are extreme.

You can think of the tectonic plates as giant pieces of puzzle that cover the Earth. They never stop moving but it is so slow we can't feel it. They progress at the rate of a couple of centimeters (between 3 and 5cms) a year!

The movement of the plates creates three types of tectonic boundaries:
  • Convergent, when plates move toward one another (also known as subduction). They can form mountain ranges like the Himalaya and the mount Everest (that keep growing over time), or trenches like the Mariana Trench in the North Pacific Ocean (deepest point on Earth)
  • Divergent, when plates move away from one another. In the ocean this process widen the oceanic floor and create a ridge.
  • Transform, when plates move alongside one another. They grind each other and create devastating earthquake.

The Different types of volcanoes:

Volcano types.
Volcano types.
Volcano types.
Volcano types.

Volcanoes appear in different sizes and variety. We can find four basic types that are characterized by the lava flow.
The lava composition ranges from very liquid to very viscous and influences directly the lava flow.

The volcano types:
  • Shield volcano are the result of liquid lava emitted from a central vent. The low viscosity lava flows rapidly over long distance forming the shield like shape volcano. Their gentle slopes usually don't exceed 10 degrees.
  • Composite volcano also known as Stratovolcanoes are the result of more viscous lava emitted from a main central vent and secondary side vents. The medium to hight viscosity lava flows slowly forming steeper slopes. Over time the hight density lava hardening rapidly builds up rising the hight of the volcano. They can explode with a great violence from the main vent as well as the side vents.
  • Dome volcano are the result of very viscous lava emitted from a central vent. The hight viscosity lava flows very slowly cooling and hardening when it reaches the surface. This phenomena create a dome like shape around and over the vent blocking the eruption. Sometimes when the pressure gets hight enough it produces violent eruption blowing the dome into pieces.
  • Caldera volcano are the result of viscous lava emitted from different vent that form over time. They form after a volcanic eruption empties a deep magma chamber causing the surface to collapse. This creates a crater like shape called caldera. They can be up to 50 kilometers wide. Over time the magma chamber can fill with magma again rising the caldera floor. It may stay like this or create another eruption reshaping the caldera and know as a resurgent caldera.

The Parts of a Volcano:

Illustration of the different parts of a volcano.
Volcanoes are composed of:
  • Magma chamber
  • Magma
  • Main vent, conduit, pipe or column
  • Side or secondary vents
  • Crater
  • Lava
  • Ash cloud or plume
  • Layers of emitted lava and ash

Different Types of Eruptions:

Volcanic eruptions can be of two types:
  • Explosive eruption is characterized by violent emissions of gas, ashes and rocks in the atmosphere (known as volcanic bomb).
  • Effusive eruption is characterized by outpouring of lava, relatively low in viscosity and gas, without significant explosion.

In more detailed classification volcanic eruptions are are of six types of increasing degree of explosiveness:
They are characterized by their volcanic activity types and location that are very often linked.
Icelandic is an effusive type with very liquid lava outpouring from long parallel fissures often building lava plateaus.
Hawaiian is similar to the Icelandic type except that the lava is flowing from the summit of a volcano creating shield volcanoes.
Strombolian is an effusive type with few outburst of ga creating relatively small explosions.
Vulcanian type involves moderate explosions creating plume cloud.
Pelean is an explosive type with low viscosity lava, pyroclastic flows and very violent explosions and destructive eruptions.
Plinian is the most intense and destructive of all. With a highly gas rich magma it creates enormous explosion and ejects a huge quantity of gas and volcanic fragments into the sky forming a devastating eruption cloud. It can be produced for several hours and rise up to the stratosphere (about 10 kilometers hight).

Interesting Facts:

  • About 90% of all active volcanoes are located in the Pacific Ring of Fire(where the Pacific plate meets other surrounding tectonic plates).
  • More than 80% of the external part of the Earth crust is made of basaltic rocks formation resulting of lava eruptions.
  • Lava creates glass called obsidian. It is a very strong rock with edges sharper than steel usually black and used for weaponry by our ancestors.
  • The hottest lava made of basalt can reach temperatures as hight as 1170 celsius degree. It is hot enough to melt any kind of metal and rocks.
  • The cloud produced by a volcano is not smoke but ash. Ash created by volcanoes is made of immensely hot gas, lava and rocks shattered into tiny pieces as small as two millimeters and extremely dangerous.
  • Volcanic ash is very dangerous for airplanes causing engines problems.
  • Volcanic lightning can appear during an eruption. It is caused by the friction of the small fragments present in the volcanic ash cloud generating static electricity.
  • The asthenosphere act as a giant moving belt induced by convection movement of temperatures and magma making the tectonic plates move.
  • Hotspots can create what is called a volcanic chain. The magma erupting creates a volcano and while the tectonic plates are moving, new volcanoes are created. This repeating process creates the volcanic chain.
  • The mid-ocean ridge is the longest mountain range on Earth. It is mostly under water and created by periodic eruptions.
  • Volcanic eruption can create lahars devastating everything on its way.

Scientific Terms:

  • Volcanology: Study of volcanoes.
  • Volcanologist: Whom study volcanoes.
  • Active volcano: A volcano that has erupted at least once in the pas 10,000 years and is expected to erupt again. It can be erupting or dormant.
  • Magma: Mix of gas and molten rocks below the Earth's surface.
  • Lava: Magma that reaches the Earth's surface.
  • Pyroclastic flow: A turbulent and very fast moving very hot mixture of gas and ash erupted from a volcano. It can reach a speed that often exceed 80 kilometers per hour with a temperature that ranges between 200 and 700 celsius degrees. It is extremely devastating.
  • Lahar: A fast moving mudflow made of volcanic ash and water. It can consume and incorporate anything in its way and grow more than 10 times its initial size. In steep areas it can exceed 200 kilometers per hour.

Jungle

Definition:

Jungle is a generic term that refers to a dense forest generally where the weather is hot.
(Jungles are very similar to rainforests but are very slightly different. In this study we will consider them the same and use both names interchangeably as they share the same features).
It is characterized by a dense tangled vegetation with an extensive biodiversity.
Jungles are one of the most important habitat on Earth and largely contribute in sustaining the Earth's ecosystem as we know it.
while each rainforest is unique, they all share common features.

Jungles are mostly situated in the tropics, subtropics and around the equator. This type of forest host an incredible biodiversity. It is though that over 50% of the plants and animals on earth live in the rainforest.
It covers about 4% of the Earth surface and 12% of the land surface in 2020. it plays an important role in the Earth's ecosystem.

How Does It Work?

Climate

Jungles precipitation is one of the highest on the globe. It fluctuate between 200 and 600 centimeters of rain a year.
The humidity is very high and average around 80%.
It never froze in the jungle. In fact, the lowest temperature is rarely below 20 celsius degrees and the highest rarely above 35 celsius degrees.
This create a hot and steamy climate that works like a greenhouse and is the perfect environment for the forest to develop. It is equable: with not much variation.

Structure
Illustration of the different layers of the rainforest.

Jungles are structured in four layers. Each level has unique characteristics corresponding to an habitat with different quantities of sunlight, water and air circulation. They are interdependent and influence one another.

  • The Emergent Layer is the top layer of the forest. Trees dominate with a hight reaching 60 meters.
  • The Canopy Layer is beneath the emergent layer. It is about 6 meters of dense vegetation with a huge network of branches and leaves forming a roof over the remaining layers.
  • The Understory Layer is a dark and more humid environment. Vegetation usually develop large leaves in order to catch the remaining sunlight reaching through the canopy.
  • The Forest Floor is the darkest part of the jungle making it difficult for the vegetation to grow. In this environment everything decays rapidly forming what is called the humus. It is the food factory for the trees of the jungle producing nutrients and hosting a thriving animal life. The humus layer is very thin making the ground poor in nutrients. For this reason the trees develop very shallow and widespread roots called buttress roots.

In the jungle trees are mostly evergreen.
In the canopy and above, animals move through the vegetation by flying or gliding. Those animals are usually small so their weight is supported by the most fragile branches.
With a particularly rich availability in food, the canopy is home to more animals than any other layers. It is estimated that the canopy host more than 50% of the life in the rainforest.
Understory plants often produce large and colorful flowers with a strong sent in order to attract pollinators in the darkest parts of the jungle.
When rivers run through the jungle, they create an unusual freshwater habitat on the forest floor. For example, the Amazon river is home to one of the few freshwater dolphin in the world.

Ecosystem and Biodiversity

The rainforests have the most important terrestrial biodiversity on Earth.
They are located in tropical regions and receive a lot of sunlight. The sunlight provide energy for the vegetation which is transmitted to all the living organisms of the jungle through the food chain.
The canopy structure provides an abundance of places for plants to grow and animals to live. It offers resources such as food and shelter that leads to interaction and interdependence of the species that live there.
The jungle is a very competitive place, with species developing incredible strategies and innovations to survive, encouraging specialization.

The jungle is home to an incredible biodiversity such as plants that only grow on other trees called epiphytes.
The climate present in the jungle allow organisms to grow at a very quick pace. And because the competition between plants is very hard and their environment harsh plants developed poisonous toxins to protect themselves from the fauna.
Some of the most known, mesmerizing and mystifying animals present in the jungle are jaguars, tigers, elephants, gorillas, monkeys, eagles and snakes that live in the trees or on the forest floor. But as well the climate their is ideal for insects such as bees, butterflies, termites, flies and ants. One particular species of ants called the army ant are nomads like! They have no nest and march in line everyday to hunt for food. When the night comes, they come together and form a nest around their queen by hooking on each other.

The Importance of the Jungle:

  • Provide home to an immense diversity of plants and animals.
  • Participate greatly in the water cycle by receiving, stocking and providing a huge quantity of fresh water. More than 50% of the precipitation it received is returned by transpiration.
  • Help to maintain the Earth ecosystem by absorbing carbon dioxide, reducing the impact of the greenhouse gas emissions. As well it produces 20% of our oxygen and absorbs solar radiation.
  • Protect against flood, erosion and drought with its unique climate and ecosystem.
  • Provide resources for food, medicine and economy like fruits, coffee, chocolate, bananas, brazil nuts, rubber, tapioca, wood etc.

The Jungle in Danger:

Illustration of the different parts of a volcano.

Deforestation is happening at an alarming pace. It is mainly due to human activity. Many scientist predict that the rainforest will lose between 5 and 10% of their species every decade. It would destruct its habitats in a near future.
This is one of the biggest challenge humanity is facing.
On the bright side, there are a lot of people invested and wanting to save the rainforests.

Interesting Facts:

  • About 25% of the medicines come from the jungle.
  • The Brazil nut tree (a vulnerable species) can live up to 1,000 years.
  • Only 2% of the light is reaching the forest floor.
  • A lot of plants in the humid climate of the rainforest canopy have developed leaves with pointy tips called drip tips so the water does not stay on the leaves avoiding the development of fungus.
  • While the forest floor layer of the jungle is very humid and still, the top layer (the emergent layer) is the dryest.
  • It can take up to 10 minutes for a drop of rain water to fall on the floor of the rainforest.
  • The largest rainforest is the Amazon, situated in South America and mostly in Brazil.

Scientific Terms:

  • Biologist: Whom is studying the field of biology.
  • Biology: Science of life and living organisms.
  • Foliage: Leafy parts of a tree or a plant.
  • Biodiversity: Variability and diversity of life on Earth from all sources. It is a measure of the diversity of species in an area or habitat.
  • Photosynthesis: Process by which plants use sunlight, water and carbon dioxide to produce glucose for their growth and reproduction, and oxygen as a waste they don't need but extremely useful for humanity!
  • Specialization: Process of adaptation of an organism in a particular way in order to thrive and/or survive.
  • Food chain: Network of links in a food web through which nutrients and energy pass from one organism to another. It describes how different organisms eat each other.

Ocean

Definition:

An Ocean is a large body of salted water. There is only one global ocean that covers 71% of the Earth surface. All the water it contains is connected.
For convenience and political reasons, oceanographers geographically divided the Ocean into five recognized basins.
Historically there are 4 ocean basins: the Pacific, the Atlantic, the Indian and the Arctic. However nowadays a fifth basins is recognized by most of the countries: the Arctic basin.

Ocean formed billions of years ago when the Earth temperature cooled below 100 Celsius degree. The water state changed from gas to water by condensing into rain. Over a long period of time it filled the basin that we call ocean.
It is commonly said that the colour of the ocean is given by the sky but in reality the colour of the ocean is blue-green. In fact, the water absorbs colours in the red spectrum of light reflecting the colours that we see. This is observable over a large quantity of water.
The salt in the ocean comes from two sources: the runoff or erosion of the land and openings in the ocean floor. Rocks on the land are the main source of salts we find in the ocean water. Rainfall and rivers that erodes the rocks on the land dissolved them and carry minerals to the seas. While some of the minerals are used by organisms found in the water, others are not. Over time this process generates an increase in their concentration making the ocean salty.

Geographic Repartition:

Map of the repartition of the oceans on Earth.

The boundaries of the ocean are mainly defined by surrounding lands. They include all the seas within their area.
The Pacific Ocean is the largest one and extends from the Antarctic region in the South to the Arctic region in the North and from Asia and Australia in the west to America in the East.
The Atlantic Ocean is the second largest and extends from the Antarctic region in the South to the Arctic region in the North and from America in the West to Europe and Africa in the East.
The Indian Ocean is the third largest and extends from the Antarctic region in the South to Asia in the North and from Africa in the West to Australia in the East.
The Southern or Antarctic Ocean is formed by combining the south parts od the previous ocean. It basically extends all around the Antarctic in a circular form.
The Arctic Ocean is the smallest and is mainly delimited by the North border of the continents that surround it.

How Does It Work?

Tides:
Illustration of the effect of the moon and the sun on the tides.

Tides are the periodic variation of the sea level caused by gravitational forces. They are caused by the gravitational pull of the moon and the sun.
It corresponds to the rise and fall of the sea level on the coast. Tides fluctuate between high and low. The difference between the two is called tidal range. It defines the intertidal zone, a particularly important ecological feature of the tides.

Almost everywhere on Earth there are two tides a day. They each have a high point (the high tide) and a low point (the low tide).
When the tide is going toward the hight tide, it is called a flood tide. And when the tide is going towards the low tide, it is called an ebb tide.

Currents:

Ocean current is a continuous movement of water. They are created by wind, water temperature, salinity and tides. They can be found on the surface of the ocean or deep down below.
Close to the surface, the currents are widely affected by the wind. Deeper, the currents are affected by temperature, pressure and salinity.

The ocean is never still. While the currents move the water from one place to another, waves are often seen on the surface of the water but they do not move the water. Waves are commonly created by the wind (but not only) and transmit energy called kinetic energy.
Rogue waves are waves that appear without being expected and have a size of more than twice of the prevailing condition.

THe Water Cycle:
Illustration of how the water cycle works.

Water is essential for life on Earth and the water cycle describes its existence and movements on the planet.
Water on Earth is present in different states: liquid, vapor and ice.
The Water on Earth is not new and is part of the cycle ever since it existed which means that the water you drink today might have been part of the snow cap of the Everest at one stage of its life!

Stages of the water cycle:
  • The sun evaporates water from the ocean: water changes state from liquid to vapor.
  • As the vapor rises into the atmosphere it cools down and the vapor condensate: water changes state from vapor to liquid forming clouds.
  • The clouds move the air current and keep charging with more water that falls back on Earth as precipitations in the state of liquid or solid (rain, snow or ice).
  • In cold climate the water is found in the solid state as snow or ice.
  • Snow and ice can melt and flow into rivers changing state from solid to liquid.
  • Snow and ice can as well directly evaporate into the air changing state from solid to vapor.
  • Rainfall and water flow from ice and snow run down and supply or create lakes, rivers and ocean.
  • Some of the flowing water goes underground by infiltration becoming groundwater.
  • Some groundwater can flow to the surface as springs.
  • Plants take and use groundwater that then evaporate by transpiration from their leaves into the air.
  • Groundwater can form some reserve very deep into the ground and can flow into the ocean.

Importance of The Ocean:

The Ocean produces over 50% of the world oxygen and absorbs 50 times more carbon dioxide than our atmosphere.
It plays an important role in the climate regulation by transporting heat from the equator to the poles.
It is an immense resource for food and economy. The ocean provides salt, fish, crustacean, seaweed minerals and energy from fossil energy to renewable energy.
Covering most part of our planet, it is hugely used for transportation.

Ocean Life:

Plankton are mostly microscopic organisms drifting and carried by the current and the tides in the ocean and unable to swim against them. It comes from the Greek for “wandering, drifting”. It comprises phytoplankton and zooplankton. Plankton has an important place in the food chain and ecosystem of the ocean.
Phytoplankton are microscopic plants. They are the main producer of oxygen performing the photosynthesis and are found close to the surface.
Zooplankton are microscopic animals including krill, sea snail etc.

The ocean is home to some incredible species from the seahorse to the narwhals (the unicorns of the ocean). They include seaweed, seagrass, mangrove, cephalopods, crustacean, corals, marine mammals, fish, sea turtles, reptiles and seabirds.
The ocean ecosystems hugely vary from the fjjords in Scandinavia to sandy beach.

Interesting Facts:

  • More than 80% of the ocean is unexplored.
  • More than 90% of the total water on Earth is in the Ocean.
  • The Pacific Ocean cover more than 30% of the Earth’s surface.
  • All the Earth land surface would fit in the Pacific Ocean.
  • Life began in the Ocean over 3.5 billion years ago.
  • Water takes about 1000 years to travel all the way around the globe.
  • The deepest part of the ocean is the Marina Trench at more than 10 kilometers deep.
  • The mid-ocean ridge is nearly 65,000 kilometers long.
  • The Great Barrier Reef in Australia is the largest living organism on Earth and can be seen from the Moon.
  • The coral reef represents only 1/50 of the marine floor.
    1/4 of marine life find its home in the coral reef.
  • The Gulf Stream transport more water than all the Earth’s rivers combined.
  • The coelacanth, a fish thought to be extinct and leaving in the ocean 300 million years ago was caught by a fisherman off the south coast of Africa.
  • The Indian ocean is the warmest ocean.
  • Tsunami waves can travel as fast as a jet plane.
  • The largest rogue waves recorded happened on the west of the coast of Scotland and presented waves with a height reaching almost 30 meters.
  • Some research shows that if all the salt from the ocean would be spread evenly on the Earth land surface, it would cover it all and build up over 150 meters high.
Illustration of the distribution of the water on the planet Earth.

Scientific Terms:

  • Seas: Smaller than ocean and usually located where the ocean and the land meet. They are partially enclosed by land and are different from ocean geographically speaking.
  • Geography: The study of Earth surface.
  • Oceanology: The study of the ocean.
  • Oceanographer: Whom study the ocean.
  • Water vapor: Gas invisible to the eye.
  • Sublimation: Water changing state from solid to vapor.
  • Deposition: Water changing state from vapor to solid.
  • Liquefaction: Water changing state from solid to liquid.
  • Solidification: Water changing state from liquid to solid.
  • Evaporation: Water changing state from liquid to vapor.
  • Condensation: Water changing state from vapor to liquid.

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