【Earth Science】Atmospheric and Oceanic Science: Common Test Success Notes
Hello everyone! Welcome to your Earth Science studies. In this chapter, we will learn about the mechanisms of the "atmosphere" (air) and the "oceans" that surround us. You might feel like "Earth Science has so much to memorize," but don't worry! The atmosphere and oceans are closely linked. If you view them as one large "system of circulation," it becomes much easier to understand. Since this is a frequent topic in the Common Test, let's focus on the key points and master them efficiently!
1. Structure of the Atmosphere: What are the "layers" of the sky?
When you look up, the sky seems to go on forever, but it is actually divided into four layers based on temperature changes. Let's look at them in order from the ground up.
(1) Troposphere (Surface to approx. 11 km)
This is where we live. Features: The temperature decreases as you go higher (dropping about 0.65℃ every 100m). Why? Because the ground is warmed by the sun, and that heat is transferred upward. Key Point: Air moves vertically here frequently, and this is the only layer where weather phenomena (rain and clouds) occur!
(2) Stratosphere (approx. 11 km to 50 km)
Features: The temperature increases as you go higher. Why? Because of the ozone layer. Ozone absorbs ultraviolet rays from the sun and releases heat, causing the air to warm up. Trivia: Since the air here is stable, this is the common flight path for large passenger jets.
(3) Mesosphere (approx. 50 km to 80 km)
Features: The temperature decreases again. This is the coldest part of the atmosphere (around -90℃).
(4) Thermosphere (above 80 km)
Features: Because it receives intense direct energy from the sun, the temperature rises sharply. Key Point: This is where auroras occur and where artificial satellites orbit.
【Pro-tip for memorizing!】 Remember the sequence from bottom to top using the rhythm: "Tro-Stra-Me-Ther" (Troposphere, Stratosphere, Mesosphere, Thermosphere)! The temperature structure follows a zigzag pattern: "decrease, increase, decrease, increase."
2. Earth's Radiation Budget: Balancing Energy
The reason Earth doesn't get too hot or too cold is that there is a balance between the energy received from the sun and the energy released by the Earth.
Solar Radiation and Terrestrial Radiation
・Solar Radiation: Light coming from the sun (mainly visible light). ・Terrestrial Radiation: Heat released by Earth into space (infrared radiation).
The Greenhouse Effect
This is a mechanism where carbon dioxide and water vapor in the atmosphere absorb infrared rays trying to escape from Earth and radiate them back to the surface. Key Point: The "greenhouse effect" is often seen as "bad," but without it, Earth's average temperature would be about -18℃. Thanks to a moderate greenhouse effect, we are able to live comfortably.
【Common Mistake】 The atmosphere is not directly heated by all the light from the sun. Remember the order: the ground is warmed first, and then that heat warms the atmosphere!
3. Atmospheric Circulation: Why does the wind blow?
Looking at the Earth as a whole, the equatorial regions are hot, and the polar regions (North and South Poles) are cold. To bridge this temperature gap, large-scale air currents (Atmospheric General Circulation) are created.
(1) The Three-Cell Model
1. Hadley Cell: Air rises at the equator and descends around 30 degrees latitude. 2. Ferrel Cell: Circulation in the mid-latitudes (near Japan). 3. Polar Cell: Cold air currents at the poles.
(2) The Coriolis Force (Deflecting Force)
This is an apparent force that acts on moving objects due to the Earth's rotation. Rule: In the Northern Hemisphere, force acts to the right of the direction of travel. Because of this, wind doesn't blow in a straight line; it curves. ・Near the equator: Trade Winds (easterly winds) ・Near Japan: Westerlies (westerly winds)
Key Point: When Japanese weather reports say "the weather will deteriorate from the west," it's because clouds are being carried by these Westerlies!
4. Science of the Oceans: Movement of Seawater
The ocean moves in a way similar to the atmosphere. There are two main types of currents.
(1) Surface Circulation (Wind-driven circulation)
Surface currents caused by winds on the ocean (Trade Winds and Westerlies). Currents near Japan: ・Kuroshio (Japan Current): A warm current from the south. It has high salinity and looks deep blue/black. ・Oyashio (Kuril Current): A cold current from the north. It is rich in nutrients.
(2) Deep Circulation (Thermohaline circulation)
A slow, global-scale current caused by cold, high-salinity seawater (like in the North Atlantic near the North Pole) becoming dense and sinking. Analogy: Imagine a giant conveyor belt that takes about 1,000 to 2,000 years to travel around all the oceans of the world.
5. El Niño and La Niña Phenomena
These phenomena, occurring near the equator in the Pacific Ocean, are frequently featured in the Common Test. They are classic examples of the interaction between the atmosphere and the ocean.
El Niño Phenomenon (Unusually warm)
1. Trade winds weaken. 2. Warm surface water spreads to the east (off the coast of Peru). 3. Sea surface temperatures off the coast of Peru rise. Impact on Japan: Often leads to cool summers and warm winters.
La Niña Phenomenon (Unusually cold)
1. Trade winds strengthen. 2. Warm surface water is pushed strongly to the west (near Indonesia). 3. Sea surface temperatures off the coast of Peru drop. Impact on Japan: Often leads to scorching summers and severe winters.
【How to remember】 Remember "whether the trade winds are strong or weak" as a pair! Wind is weak = warm water doesn't move = El Niño Wind is strong = warm water is blown west = La Niña
Summary: Master these points!
・The atmosphere has a 4-layer structure from the bottom up: Troposphere, Stratosphere, Mesosphere, and Thermosphere. ・Earth's temperature is maintained by the radiation budget, balancing energy received from the sun with infrared radiation released. ・Winds in the Northern Hemisphere curve to the right due to the Coriolis Force, and the Westerlies blow above Japan. ・The ocean has surface circulation driven by wind and deep circulation driven by density differences. ・El Niño is a phenomenon where trade winds weaken and water temperatures off the coast of Peru rise.
It might be overwhelming at first with so many terms, but try drawing diagrams and visualizing how "air moves this way, so the ocean moves that way." Take it one step at a time, and it will definitely become a strength of yours. You can do it!