What percentage of Earth's atmosphere is nitrogen?
78%
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What percentage of Earth's atmosphere is oxygen?
20.95%
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What is atmospheric pressure at sea level (in mmHg)?
760 mmHg
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What is air pressure per square inch at sea level?
Nearly 15 pounds per square inch
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How do you calculate partial pressure?
Multiply total atmospheric pressure by the decimal percentage of that component (Example: Nitrogen = 760 mmHg x 0.78084)
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How does atmospheric pressure change with altitude?
Atmospheric pressure decreases as altitude increases due to less air column above
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What is the troposphere?
The lowest layer of the atmosphere, next to Earth's surface and home to most weather
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What is the stratosphere?
The layer above the troposphere, home of the ozone layer
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What is the mesosphere?
The middle layer where meteorites often burn up due to denser air
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What is the thermosphere?
The uppermost atmospheric layer which gets very hot
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What is the ionosphere?
A sublayer in the thermosphere where auroras (Northern and Southern Lights) occur due to solar ionization
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What is the exosphere?
The layer beyond the thermosphere
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What is partial pressure of nitrogen at sea level?
593.4 mmHg
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What is partial pressure of oxygen at sea level?
159.22 mmHg
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How high does the column of air extend that creates atmospheric pressure?
About 700 km
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What causes the Aurora Borealis and Aurora Australis?
Solar energy causing ionization in the ionosphere
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What determines how the layers of the atmosphere are defined?
They are defined by temperature, though density changes with altitude (becoming less dense higher up)
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What percentage of the atmosphere is composed of gases other than nitrogen and oxygen, plus water vapor and dust?
About 1%
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What creates global winds?
Solar energy leading to convection cells
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What happens to meteors in the mesosphere?
They usually burn up due to friction
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What is ozone?
Oxygen changed from O2 to O3
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Why is the ozone layer crucial?
It absorbs potentially harmful UV radiation, making life possible on Earth's surface
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Why doesn't the thermosphere feel hot despite high temperatures?
The atmosphere is so thin that not much heat is released
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What happens to particles in the ionosphere?
They become electrically charged (ions) by absorbing energy, stopping it in the upper atmosphere
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What acts like a shield in space to protect Earth?
Earth's magnetic field (and the Sun's magnetic field further away)
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What are the main ways Earth is protected from dangerous solar energy?
Ionosphere absorbs some energy, atmosphere burns up solids, and ozone absorbs UV energy
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What is the source of all energy in the atmosphere?
The Sun
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What are the three ways energy is transferred to Earth and throughout the atmosphere?
Radiation, conduction, and convection
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What is the greenhouse effect?
The heating of the lower atmosphere from radiation absorbed by heat-absorbing gases
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Why is the greenhouse effect important for life?
Without it, Earth would not be habitable - it allows life to flourish by trapping heat
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How does the greenhouse effect work?
The atmosphere traps thermal (heat) energy and reflects it back to Earth
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What do scientists think about increased greenhouse gases?
They may be part of the cause of global temperature changes and accelerating those changes
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What role do the atmosphere's layers play in protection?
All layers provide protection through particles present, friction, absorbing energy, and other mechanisms
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What gas is of particular concern for increasing the greenhouse effect?
Carbon dioxide
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What are the three main ways the atmosphere protects us?
1) Ions stopped in thermosphere, 2) Objects burn up in atmosphere, 3) Ozone blocks UV radiation
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Why can the magnetic field protect Earth in ways the atmosphere cannot?
Because it affects charged particles, while the atmosphere is relatively inert
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What generates Earth's magnetic field?
Heat making the outer core convect
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What makes magnetic fields in general?
They are made wherever there is an electric current (movement of electrons)
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How thick is Earth's liquid outer core?
2270 km
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What is the diameter of Earth's solid inner core?
2400 km
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What are both cores made of?
Iron and nickel
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How fast does molten iron flow in Earth's core?
About 0.8 inches per second
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How strong is Earth's magnetic field in Gauss?
0.4 Gauss, weaker than a small hand-held magnet
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How far does Earth's magnetic field extend into space?
7-10 times Earth's diameter
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What shape is Earth's magnetic field and why?
Tadpole-shaped because solar wind compresses it on the sun-facing side and stretches it into a tail on the opposite side
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What is the solar wind?
Extremely hot, high-energy, fast-moving charged particles (mainly protons with positive charge) given off by the sun
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What would happen without Earth's magnetic field?
All life would die as the magnetic field is needed to channel away solar wind and block dangerous radiation
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What percentage of the Sun's energy reaches Earth?
Less than 1%
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What else does the magnetic field prevent besides radiation damage?
Prevents erosion of the atmosphere by the solar wind
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What can happen to Earth's magnetic poles?
They can reverse or "flip" for unknown reasons
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What unique ability do some animals have regarding Earth's magnetic field?
They can sense it and use it for navigation
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How is Earth's core magnetic field generated differently from a bar magnet?
Bar magnets generate fields from electrons orbiting iron atom nuclei all in the same direction, while Earth's field comes from electrical currents in the molten iron core
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What are the three ways energy is transferred in the atmosphere?
Radiation, conduction, and convection
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What is radiation?
The transfer of energy as electromagnetic waves
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What is thermal conduction?
The transfer of thermal energy through a material
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What is the greenhouse effect?
The process by which gases in the atmosphere absorb thermal (heat) energy and radiate it back to Earth
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What wavelength energy passes easily through the atmosphere?
Short wavelength energy
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What wavelength energy has difficulty escaping the atmosphere?
Long wavelength energy
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What percentage of greenhouse gases is made up of the top five gases?
98%
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What is the most abundant greenhouse gas and its percentage?
Carbon dioxide at 56%
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What is the second most abundant greenhouse gas and its percentage?
Methane at 16%
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What percentage of greenhouse gases are CFCs and what is their origin?
13%, and they are man-made
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What percentage of greenhouse gases is ozone?
7%
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What percentage of greenhouse gases is nitrous oxide?
6%
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What is needed for Earth to be livable regarding energy balance?
The amount of energy Earth receives must be approximately equal to the amount of energy returned to space
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How much of the Sun's total energy output reaches Earth?
A fraction of a percent
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List the five main greenhouse gases in order of abundance
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