South 고등학교 2학년 Earth Science
Chapters: 3
1. Atmosphere-ocean interaction
Physical and chemical properties of seawater · Deep ocean circulation · Mid-latitude cyclones and anticyclones · Typhoons · El Niño and La Niña · Causes of climate change
- Water (Oceans): Hydrological Cycle, Ocean Floor, Temperature and Salinity – The Earth's water keeps moving between oceans, air, land and living things in the hydrological (water) cycle; about 97% of it is in the oceans. The ocean floor has major divisions — continental shelf, continental slope, deep sea plain and ocean deeps (trenches) — and minor features like mid-ocean ridges, seamounts, guyots, submarine canyons, atolls and banks. Ocean surface water is warmest near the equator and colder towards the poles; with depth it falls sharply through a layer called the thermocline, below which the water is near 0–4 °C. Salinity is the salt in sea water, about 35 grams per 1,000 grams (35‰). It rises with evaporation and falls with rain, rivers and melting ice, so it is high in the subtropics and enclosed hot seas and low near the equator, poles and river mouths.
- Movements of Ocean Water: Waves, Tides and Currents – Ocean water moves in three ways. Waves are made mostly by wind: the energy moves forward while each bit of water goes round in a small circle; waves slow down and break in shallow water. Tides are the regular rise and fall of the sea, usually twice a day, caused by the Moon's (and Sun's) pull and the Earth–Moon spin. When Sun, Moon and Earth line up (new and full moon) we get very high spring tides; when they are at right angles (quarter moons) we get weak neap tides. Ocean currents are huge rivers of water flowing in fixed directions, pushed by winds, heating, gravity, salinity and density differences, and turned by the Coriolis force. Warm currents flow from the equator towards the poles; cold currents flow from the poles towards the equator. Currents change coastal climates, fishing, fog and shipping.
- Atmospheric Circulation and Weather Systems – Air has weight, so it presses down: this is air pressure (about 1013 mb at sea level). Wind blows from high pressure to low pressure, pushed by the pressure gradient force, turned by the Coriolis force (right in the north, left in the south) and slowed by friction near the ground. Uneven heating makes pressure belts (equatorial low, subtropical highs, subpolar lows, polar highs) and three circulation cells, giving planetary winds: trade winds, westerlies and polar easterlies. Belts shift with the seasons, giving seasonal winds like the monsoon; local winds include land and sea breezes and mountain and valley winds. Big bodies of air with the same temperature and moisture are air masses; where two meet is a front. Cyclones are low-pressure storms: tropical cyclones form over warm seas; extratropical ones form along fronts. Thunderstorms and tornadoes are small but violent storms.
- Earth's Geography and Climate: Rain Shadows, El Niño and La Niña – Climate depends on geography. Latitude sets how much sunlight arrives; air rising at the equator and sinking near 30° makes rainforests and deserts (the Hadley cell). Altitude cools air about 6.5 °C per km. Oceans warm and cool slowly, so coasts have milder climates, and ocean currents carry heat. Mountains force moist wind upward, giving rain on the windward side and a dry rain shadow behind. El Niño is when Pacific trade winds weaken and warm water spreads east, shifting rain and changing weather worldwide; La Niña is the opposite, with stronger trade winds and a colder east Pacific.
- Climate Change and the Greenhouse Effect – Climate is the average weather of a place over about 30 years. Greenhouse gases like carbon dioxide and methane trap some of the heat the Earth gives off. Humans have added a lot more of these gases by burning fossil fuels and cutting forests, so the Earth is warming. This causes melting ice, rising seas and more extreme weather. We can cut emissions (mitigation) and prepare for changes (adaptation).
2. Earth history and rocks of the Korean Peninsula
Relative dating of strata · Geological periods · Magma and igneous rocks · Metamorphism · Korea's geoparks
- Igneous Rocks: From Hot Magma to Solid Stone – Igneous rocks form when melted rock cools and turns solid. Melted rock underground is magma; on the surface it is lava. Magma forms where rock gets hot enough, or where pressure drops or water is added, mostly at plate boundaries and hot spots. Magma is lighter than solid rock, so it rises. If it cools slowly deep underground, crystals grow big (intrusive rocks such as granite and gabbro). If it cools fast at the surface, crystals stay tiny or glass forms (extrusive rocks such as basalt, rhyolite, obsidian and pumice). Silica content decides colour and stickiness: low-silica (mafic) magma is dark, hot and runny and erupts gently; high-silica (felsic) magma is light, cooler and sticky, traps gas and erupts explosively.
- Metamorphic Rocks and Metamorphism – Metamorphic rocks form when an existing rock (the parent rock) is changed by high temperature, high pressure and hot fluids while staying solid. Minerals grow, change and line up. Directed pressure makes foliated rocks (slate, phyllite, schist, gneiss); heat without squeezing makes non-foliated rocks (marble, quartzite, hornfels). Regional metamorphism happens where plates collide; contact metamorphism happens next to hot magma.
3. Solar system bodies, stars and cosmic evolution
Eclipses in the Sun-Earth-Moon system · Spectral classes of stars · Stellar evolution by mass · Hubble's galaxy classification · Hubble-Lemaître law
- Stars: Colour, Brightness, Distance and the H-R Diagram – A star is a huge ball of hot gas that shines by nuclear fusion. Its colour shows its surface temperature: red stars are cool, blue stars are hot (Wien's law: λmax × T = 2.9 × 10⁻³ m K). Stars are sorted into spectral classes O B A F G K M, hottest to coolest. How bright a star looks (apparent magnitude) depends on its real power (luminosity) and its distance, because light weakens as 1/d². Nearby distances are found by parallax: d (pc) = 1/p (arcsec). Luminosity depends on size and temperature (L = 4πR²σT⁴). The H-R diagram plots luminosity against temperature and shows the main sequence, giants and white dwarfs.
- Stars and Galaxies: From Starlight to the Big Bang – Everything we know about stars comes from their light. Splitting starlight into a spectrum shows dark lines that tell us which elements a star has; the colour tells us its temperature (blue = hot, red = cool) and stars are sorted into classes O B A F G K M. The H-R diagram plots true brightness against temperature: most stars, including the Sun, lie on the main sequence, with giants top right and white dwarfs bottom left. A star is born in a nebula and its mass decides its life: a Sun-like star becomes a red giant and then a white dwarf; a star of more than about 8 solar masses becomes a supergiant, explodes as a supernova and leaves a neutron star or black hole. Stars gather in galaxies, which are spiral, elliptical or irregular. Distances are huge, so we use the astronomical unit, the light-year and the parsec. Galaxies are moving apart, faster when farther (Hubble's law), which together with the cosmic microwave background supports the Big Bang about 13.8 billion years ago.
- Cosmology: The Expanding Universe and the Big Bang – Cosmology is the study of the whole universe: its structure, history and future. Galaxies gather in groups, clusters and filaments around huge voids. Distant galaxies are moving away from us, faster the farther they are (Hubble's law, v = H₀d), because space itself is expanding. Running the expansion backwards leads to a hot, dense beginning about 13.8 billion years ago, the Big Bang. The main evidence is redshift, the cosmic microwave background and the amounts of hydrogen and helium. Most of the universe is dark matter and dark energy.