CH. 10 PLANETARY ATMOSPHERES. Mercury Made of: helium, sodium, oxygen No weather-there’s not enough atmosphere! 10.1 PLANETARY ATMOSPHERES.

CH. 10 PLANETARY ATMOSPHERES

MercuryMade of: helium, sodium, oxygen

No weather-there’s not enough atmosphere!

10.1 PLANETARY ATMOSPHERES

VenusMade of: mostly Carbon dioxide (96%) and a little Nitrogen (3.5%)

Weather-slow winds with no big storms and lots of acid rain from sulfuric acid clouds

10.1 PLANETARY ATMOSPHERES

EarthMade of: mostly

Nitrogen (77%) lots of Oxygen (21%), argon, water vapor, and other trace elements

Wind over the whole planet-global wind patterns, storms, hurricanes

Clouds made of water vapor

10.1 PLANETARY ATMOSPHERES

MarsMade of: mostly Carbon dioxide (95%), Nitrogen (2.7%) and Argon (1.6%)

Weather-some wind and dust storms, but there is very little pressure and the atmosphere is very thin

10.1 PLANETARY ATMOSPHERES

Video from Discovery Streaming

WEATHER ON MARS

What is an atmosphere?the layer of gases that

surround a world can be either molecules or

atoms which create pressure-we feel the pressure of 1 atm, on Venus we would feel the pressure of 90 atmospheres

Where does the atmosphere end?

There’s not a specific ending place-it kind of fades away

10.1 PLANETARY ATMOSPHERES

3 things that would determine how sunlight would heat a planet with no atmosphere:

1. Distance from the Sun the closer it is, the more energy

from sunlight reaches the surface2. How much sunlight the

planet absorbs vs. refl ects3. How fast the planet

rotates if it has a short day, the

temperatures will be more even than if there is a really long day

10.2 ATMOSPHERIC STRUCTURE

How does an atmosphere keep a planet warm?

Gases can absorb infrared light and heat up

Greenhouse gases trap infrared radiation and this helps heat the lower atmosphere (where we live!)

The greenhouse gases are gases that are good at absorbing infrared light: Water vapor Carbon dioxide Methane

10.2 ATMOSPHERIC STRUCTURE

Is the greenhouse

effect a good thing or a bad thing?Explain.

Reminders: Pay your $5

Turn in permission THIS WEEK!

DMA#5 10/9/12

Layers of the atmosphere

10.2 ATMOSPHERIC STRUCTURE

7. How does the fact that our atmosphere scatters light benefit us? What would it be like if our atmosphere didn’t scatter light?

Without scattering we would be able to see the stars during the daytime!

Also, shadows would be pitch black, so walking down the alley in a big city would be like night!

10.2 ATMOSPHERIC STRUCTURE

Why is the sky blue?

Light scattering makes the sky appear blue

Blue light is scattered while the red light goes straight through the atmosphere

10.2 ATMOSPHERIC STRUCTURE

Why do sunsets appear red?Sunlight passes through more

atmosphere to reach you-most of the blue light is “scattered away” leaving the red behind.

10.2 ATMOSPHERIC STRUCTURE

Describe how the greenhouse eff ect works and why it is important to life on Earth.

Light from the sun warms the atmosphere and ground

The “greenhouse” gases absorb heat, then re-emit it in all directions

This helps heat the surface and keeps the troposphere warm

Importance?Because it keeps us warm and

regulates our temperatures so we don’t have very extreme temperature shifts

10.2 ATMOSPHERIC STRUCTURE

 Why is the stratosphere called the stratosphere?

 There isn’t any convection, so the air isn’t moving much and becomes layered-AKA stratifi ed

Airplanes glide smoothly here because of the lack of air movement.

How does the ozone in the stratosphere benefi t us?

It absorbs most of the Sun’s UV radiation, which is very damaging to us

10.2 ATMOSPHERIC STRUCTURE

Figure 10.9a. Which one of the

three planets shows the biggest temperature increase due to the greenhouse eff ect?

b. Which planet has the most uniform temperature from high to low altitude?

c. Is the Earth’s temperature higher at and altitude of 25km or 50km?

10.2 ATMOSPHERIC STRUCTURE

Why is the magnetosphere so important to us?

Solar wind = charged particles from the Sun

The magnetosphere will either divert those particles or trap them in the Van Allen Belts

10.3 MAGNETOSPHERES AND THE SOLAR WIND

They can produce beautiful auroras in the North and South poles-where the North and South poles of the magnetosphere come close to the Earth’s surface

14. What is the diff erence between weather and climate?

Weather is the varying conditions and combinations of wind, clouds, temperature, and pressure

Can change with the seasons and atmospheric conditions, can vary dramatically by the month, day or even hour

Climate is the long term average of all the weather in an area and generally stays the same over long periods of time

 10.4 WEATHER AND CLIMATE

15. Why doesn’t Venus experience seasons?

Because it isn’t tilted! Both hemispheres stay in the same location relative to the Sun.

10.4 WEATHER AND CLIMATE

What are the 2 major factors aff ecting global wind patterns?

1. Atmospheric heating: the air at the equator heats and expands, then fl ows towards the poles and sinks, creating convection cells

Let’s compare Earth and Venus…

10.4 WEATHER AND CLIMATE

The circulation of the Venusian atmosphere is dominated by two huge convection currents in the cloud layers, one in the northern hemisphere and one in the southern hemisphere

What are the 2 major factors aff ecting global wind patterns?

2. Planetary rotation: basically the rotation of the planet pushes the air sideways-called the Coriolis eff ect

10.4 WEATHER AND CLIMATE

How does the Coriolis eff ect change the shape and movement of the circulation pattern of winds on Earth? Breaks up the convection cells so there are 6 instead of 2 (3 per hemisphere)

Causes air to circulate counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere

10.4 WEATHER AND CLIMATE

Similarities:

Sun warms the atmosphere at the equator and creates convection cells

Clouds are always present

Clouds contain water

Rain forms and falls

Differences:

On Venus-Clouds contain Sulfuric acid mixed with the water(both of these are replenished by volcanic eruptions)

Rain that falls evaporates long before it hits the ground

10.4 WEATHER AND CLIMATEEARTH VS. VENUS: CLOUDS AND

PRECIPITATION

MarsClouds can form-

especially over its big volcano-Olympus Mons

Barely any water in the atmosphere, but there is some hidden under the polar CO2 ice caps

There may be more water under the surface that helps form the geologic features of Mars

10.4 WEATHER AND CLIMATE

How are atmospheres created?

From 3 diff erent processes Outgassing-the outpouring of gases from the earth's interior

Evaporation/sublimation-surface liquids evaporate into the atmosphere

Bombardment-micrometeorites can create only a very thin atmosphere, this is the main source of atmosphere for the Moon and Mercury

 10.5 ATMOSPHERIC ORIGINS

AND EVOLUTION

20. What is outgassing? Why is it important?

It’s important because it helps create and replenish atmospheres

21. What are some ways an atmosphere can lose gas? Thermal escape-a molecule moves fast

enough to escape gravity Bombardment Atmospheric cratering Condensation Chemical reactions

10.5 ATMOSPHERIC ORIGINS AND EVOLUTION

What are the 3 things that determine if a gas can be lost by thermal escape?

1. The planet’s escape velocity-the larger the planet the stronger the gravity

2. Temperature-higher temperature means faster movement

3. Mass-it’s easier for lighter particles to move fast enough to escape

10.5 ATMOSPHERIC ORIGINS AND EVOLUTION

23. The Moon and Mercury: what is their only source of new gas?

Bombardment from micrometeorites

How do they lose gas particles?

Both are small so they have low gravitational pull and the particles can move fast enough to escape

Other times they are stripped away by solar wind

 10.6 HISTORY OF THE

TERRESTRIAL ATMOSPHERES

24. Mars: what stripped away the majority of its atmosphere?

it’s possible that Mars used to have a thick atmosphere from volcanic outgassing

As the planet cooled it lost its magnetosphere

the atmosphere was then stripped away by the solar wind

10.6 HISTORY OF THE TERRESTRIAL ATMOSPHERES

 25. Venus: Why is it hotter than Mercury even though it is further from the Sun?

What is one piece of evidence that Venus may have once had a lot of water vapor in its atmosphere?

An unusually high amount of deuterium-an isotope of hydrogen that can be left behind when water molecules are broken apart by UV radiation.

10.6 HISTORY OF THE TERRESTRIAL ATMOSPHERES

 Reflection-Answer in your notebooks What makes our atmosphere so unique and suitable for life?

Give at least 4 pieces of evidence to support your claim.

Include information on the atmospheres of at least 2 other terrestrial planets in comparison with Earth.

TERRESTRIAL ATMOSPHERES