July: My Best Friend from School
July: My Best Friend
July is a really good friend of mine. She is my friend from school.
We're both in the same crowd, and we all go out quite often.
Her Appearance
July is short and very slim. She has fair skin and beautiful green eyes.
Charlie thinks she's quite attractive. Her hair is straight and shoulder-length.
Her Personality
She has a bit of a sense of humor. She can be a bit bossy, but I don't mind, because she's such great company.
She's generous and helpful, and I can always count on her to be there when I need her.
Her Free Time
In her free time, she goes out with her friends and goes to parties.
She is now studying in high school.
My Opinion
In my opinion, she is the best person and the best friend I could have.
Earth's Composition and Structure
Atmosphere: Nitrogen: 78.1%, Oxygen: 20.9%, CO2: 0.03%, Other gases: trace amounts.
Lithosphere
The Earth's crust is a rigid layer, variable in thickness between 10 and 50 km, made up mainly of silicates integrated with the upper part of the mantle.
Lithospheric plates: These are divided into plates that move between 2 and 20 cm per year, driven by convection currents that take place in the asthenosphere.
Greenhouse Effect
The increase in the temperature of the atmosphere occurs as a result of the concentration of the main greenhouse gases in the atmosphere, such as carbon dioxide (CO2).
Convection
Convection is produced by temperature and density differences: warmer materials rise, while colder, denser materials sink.
Moho Discontinuity
The Moho is a sudden change in seismic wave velocity, stabilizing the separation between the crust and the mantle. Waves do not propagate through it, and the Moho produces sudden changes in wave speed between the mantle and the outer core.
Wegener and Continental Drift
Alfred Wegener, a German scientist, presented the theory of continental drift. This theory states that, about 200 million years ago, the continents were united in one supercontinent called Pangea. Despite his evidence, he could not explain the mechanism responsible for the movement of the continents.
Supporting Evidence
- Geographic: The shapes of the continents coincided.
- Paleontological: Identical fossils of organisms have been found in places today thousands of kilometers apart.
- Geological and tectonic: If the continents are joined, the types of rock formations can be observed as nearly continuous.
- Paleoclimatic: Discovered glaciers whose climates do not coincide with current ones.
Other Features
Ocean Ridges: Large submarine elevations located in the central part of the Earth's oceans.
Consequences: The dynamics of lithospheric plates are a consequence; subduction and collision of plates have important thermal and mechanical effects.
Energy and Radioactivity
At the beginning of the 20th century, radioactivity was discovered. Its existence was initially considered to be heat as a product of the disintegration of unstable isotopes (Uranium and Thorium). They emit particles that collide with the atoms of minerals and heat them.