GED Science Atmosphere, Oceans, and Earth's Interior Summary

Earth has four main layers. The crust is the thin, rocky outer layer we live on. Below it are the mantle, the liquid outer core, and the solid inner core.

Wrong choices

• Inner core: The inner core is solid metal at the center of Earth.
• Mantle: The mantle lies below the crust. It is hot rock that slowly flows.
• Outer core: The outer core is liquid metal deep inside Earth.

Dry air is about 78% nitrogen and about 21% oxygen. The rest is mostly argon, with small amounts of carbon dioxide and other gases.

Wrong choices

• Carbon dioxide: Carbon dioxide is a very small part of the air, well under 1%.
• Hydrogen: Hydrogen gas is almost absent from the lower atmosphere.
• Oxygen: Oxygen is about 21% of the air, the second most common gas.

The ozone layer is in the stratosphere. Ozone absorbs much of the Sun's ultraviolet (UV) radiation, which can damage skin, eyes, and living cells.

Wrong choices

• It blocks all sunlight from reaching the ground.: Visible sunlight passes through the ozone layer. Only much of the UV is absorbed.
• It traps heat to keep Earth warm at night.: Trapping heat is the greenhouse effect, mainly caused by gases such as water vapor and carbon dioxide.
• It makes rain fall on dry areas.: Rain forms from water vapor in clouds in the lower atmosphere.

Earth's crust is broken into large tectonic plates that move slowly. Where plates pull apart, push together, or slide past each other, rocks break and magma can rise. So most earthquakes and volcanoes are found near plate boundaries.

Wrong choices

• Only in deserts: Earthquakes and volcanoes are not limited to deserts.
• In the middle of tectonic plates: A few occur away from plate edges (such as Hawaii's volcanoes), but most happen at boundaries.
• Only near the North and South Poles: Earthquakes and volcanoes are not limited to the poles.

Sunlight warms the ground, and the ground gives off heat (infrared radiation). Greenhouse gases absorb some of this heat and keep it near the surface. More greenhouse gases trap more heat, which warms the climate.

Wrong choices

• A hole in the ozone layer lets extra heat into the atmosphere.: The ozone layer is about UV radiation. The greenhouse effect is about gases trapping heat.
• The Sun gives off more energy at night.: The Sun's output does not change between day and night. Night is when our side of Earth faces away from the Sun.
• Greenhouse gases block all sunlight from reaching the ground.: Sunlight reaches the ground. Greenhouse gases trap some of the heat that the ground gives off.

1. Change from 1990 to 2020: 414 − 354 = 60 ppm.
2. Number of years: 2020 − 1990 = 30.
3. Average rate: 60 ÷ 30 = 2.0 ppm per year.

The rate from 1990 to 2020 (2.0) is faster than from 1960 to 1990 (about 1.2), so the increase sped up.

Wrong choices

• 1.6 ppm per year: 1.6 is the average from 1960 to 2020 ((414 − 317) ÷ 60), not from 1990 to 2020.
• 60 ppm per year: 60 ppm is the total increase from 1990 to 2020. It must be divided by 30 years.
• 1.2 ppm per year: 1.2 is the average from 1960 to 1990 ((354 − 317) ÷ 30).

Physical weathering breaks rock into smaller pieces or wears it down without changing its minerals. Wind-blown sand, ice wedging in cracks, and flowing water are common causes.

Wrong choices

• Deposition: Deposition is when wind or water drops sediment in a new place, not when rock is worn down.
• Chemical weathering: Chemical weathering changes the rock's minerals, as when acid rain dissolves limestone. Here the rock's makeup does not change.
• Volcanic activity: Volcanic activity builds new rock from magma. It does not wear rock down.

Ocean currents move heat around the planet. A warm current heats the air above it, and winds carry that warmth over nearby land. This gives coastal western Europe milder winters than other places just as far north.

Wrong choices

• It causes earthquakes along the coast.: Ocean currents do not cause earthquakes. Moving plates do.
• It makes nearby rivers saltier.: Ocean currents do not make river water salty.
• It makes the climate much colder than it would be otherwise.: A warm current brings warm water, so it warms the nearby land, not cools it.

Uneven heating of Earth's surface creates areas of high and low air pressure. Air moves from high pressure toward low pressure, and that movement is wind. Earth's rotation bends the paths of large wind systems.

Wrong choices

• from areas of low air pressure toward areas of high air pressure: This is reversed. Air moves from high pressure to low pressure.
• straight up from the ground into space: Wind is the mostly sideways movement of air across Earth's surface.
• only from north to south: Winds blow in many directions, depending on where high and low pressure are.

Corals depend on algae that live in their tissues and give them food and color. When water is too warm for too long, corals expel the algae and turn white. If the heat lasts, the corals can starve and die.

Wrong choices

• Ocean acidification: Ocean acidification is the ocean becoming more acidic as it absorbs carbon dioxide. It is a different process, although it also harms corals.
• Coral spawning: Coral spawning is how corals reproduce.
• Sea-floor spreading: Sea-floor spreading is the formation of new ocean crust at mid-ocean ridges.