CH. 10 PLANETARY ATMOSPHERES... HAHA

atmospheric pressure

- depends on both density and temperature. - Adding air molecules increases the pressure - Heating the air also increases the pressure. ======================= - Pressure and density decrease with altitude because the weight of overlying layers is less (The higher you go in atmosphere, the less weight of the gas above you thus- less pressure.)

All of the following have occurred over long periods of time on Earth. Which one is not thought to have played a major role in long-term changes in Earth's climate?

A gradual rise in the atmospheric content of oxygen.

Which of the following best describes how the greenhouse effect works?

A planet's surface absorbs visible sunlight and returns this absorbed energy to space as infrared light. Greenhouse gases slow the escape of this infrared radiation, which thereby heats the lower atmosphere.

Why is the Coriolis effect so weak on Venus?

Because Venus rotates so slowly.

Why is thermal escape of atmospheric gas much easier from the Moon than from Earth?

Because the Moon's gravity is so much weaker than Earth's. Thermal escape depends on escape velocity, which is lower for weaker gravity.

Which way do storm systems circulate in the Southern Hemisphere?

Clockwise

Losses of Gas

Condensation onto surface Chemical reactions with surface Large impacts blast gas into space

Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal?

Cooler temperatures lead to slower formation of carbonate minerals in the ocean, so carbon dioxide released by volcanism builds up in the atmosphere and strengthens the greenhouse effect. This feedback mechanism would indeed warm the planet back up.

Coriolis Effect on Earth

Direction of circulation depends on hemisphere • N: counterclockwise / right S: clockwise / left

Why does Earth have so little carbon dioxide in its atmosphere compared to Venus?

Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere.

exosphere

Gas particles in Earth's atmosphere most easily escape from the

What is the main reason why Venus is so much hotter than Earth and Mercury?

Greenhouse effect is much stronger on Venus than on Earth. distance is another reason

What key process underlies why Mars changed so much from its early conditions to its conditions today?

Interior cooling. Cooling of the interior explains both why core convection stopped, leading to weakening of the magnetic field and magnetosphere, and why volcanism and outgassing became so much weaker.

What happens to the energy that the ground absorbs in the form of visible sunlight?

It is returned upward in the form of infrared light.

Why doesn't Mars have a stratosphere?

It lacks a layer of ultraviolet absorbing gas.

What is the importance of the carbon dioxide (CO2) cycle?

It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.

All of the following statements are true. Which one explains why Mars has lost so much more interior heat than Earth.

Mars is smaller than Earth. Smaller objects cool more rapidly than large ones, so Mars's smaller size explains why it has lost much more interior heat than Earth.

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

Mars lost any global magnetic field that it may once have had. This allowed the solar wind to strip atmospheric gas into space.

Does Venus have auroras around its poles, like Earth? Why or why not?

No, because it lacks a global magnetic field. Venus rotates too slowly to generate a global magnetic field, and hence it does not have a magnetosphere or auroras.

Sources of Gas

Outgassing from volcanoes Evaporation of surface liquid; sublimation of surface ice Impacts of particles and photons eject small amounts of gas

All the following statements are true. Which one explains why convection can occur in the troposphere but not in the stratosphere?

Temperature declines with altitude in the troposphere but increases with altitude in the stratosphere.

Where Does an Atmosphere End?

There is no clear boundary b/w the atmosphere and space above. But at some point, the density becomes so low that we can't think of the gas as air anymore. Collisions b/w atoms and molecules are rare at this altitude, and the gas is so thin that it would look and feel as if u'd already entered space, occurring at an altitude of about 100 km.

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?

They calculate this temperature from Earth's reflectivity and distance from the Sun.

moon and mercury

They have thin exospheres only, with gas coming from impacts of subatomic particles and photons.

Which of the following best explain what we think happened to outgassed water vapor on Venus?

Ultraviolet light split the water molecules, and the hydrogen then escaped to space.

Which planet(s) have an atmosphere that consists mostly of carbon dioxide?

Venus and Mars

Which of the following general statements about light and Earth's atmosphere is NOT true?

Visible light from the Sun is absorbed in the exosphere.

greenhouse effect

Visible light passes through atmosphere and is absorbed by the planet's surface • Warm surface emits IR radiation to cool • CO2 and other greenhouse gases absorb IR light from surface, trapping heat

Which of the following is the most basic definition of a greenhouse gas?

a gas that absorbs infrared light

What do we mean by a runaway greenhouse effect?

a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere

Earth's atmosphere

about 100km thick Consists mostly of molecular nitrogen (N2) and oxygen (O2)

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________.

absorb infrared light emitted by the surface

earth's stratosphere

absorbs most of the ultraviolet light arriving here from the Sun.

What would happen to Earth's temperature if Earth were more reflective?

b) It would go down.

Why does the Moon have (almost) no atmosphere?

b) It's gravity is too low to retain an atmosphere

A planet's surface temperature is determined by

balance between the energy of sunlight it absorbs and the energy of outgoing thermal radiation rotation, reflectivity, and distance

The most common atmospheric gas for the terrestrial planets is

carbon dioxide

Which way do winds rotate around high pressure systems in the southern hemisphere?

counter clockwise

Why is the sky blue?

d) Air molecules scatter blue light more than red light. b/c sunsets are red

Which statement best describes the atmosphere of Mars?

d) much thinner than the Earth's with a different composition

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space?

infrared light emitted by the surface and atmosphere visible light reflected by clouds visible light reflected by the surface

The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________.

is temporarily absorbed by greenhouse gases and then reemitted in random directions

Most of the charged particles from the Sun are deflected around Earth by the

magnetosphere

The most common atmospheric gas for the Earth is

nitrogen at 77% 2nd is oxygen at 21%

Which two factors are critical to the existence of the carbon dioxide (CO2) cycle on Earth?

plate tectonics and liquid water oceans Carbon dioxide dissolves in the oceans and becomes incorporated into carbonate rock; plate tectonics recycles the carbonate rock into the mantle, where it melts and releases its gas back to the atmosphere.

Which characteristic of Earth explains why we have an ultraviolet-absorbing stratosphere?

the existence of photosynthetic life Photosynthesis released the oxygen in our atmosphere, and oxygen allows ozone (a form of oxygen) to be made in the stratosphere.

Based on everything we have learned about Venus and Mars, what is the most surprising aspect of Earth's climate history?

the fact that the temperature of our planet has remained relatively steady throughout our planet's history

Most of the X-rays coming from the Sun are absorbed in the

thermosphere

The densest layer of the atmospheres of Venus, Earth, and Mars is the

troposphere

earth's atmospheric structure from the ground to up

troposphere stratosphere thermosphere exosphere

Which planet or moon has the highest average surface temperature?

venus

highest to lowest pressure/ & gas

venus earth mars mercury

The energy that warms Earth's surface comes primarily in the form of __________.

visible light from the Sun

Which of the following is NOT an expected consequence of global warming?

warming up of the entire Earth by the same amount

Suppose that Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be _______.

well below the freezing point of water