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Essential Question: What is the significance of the atmosphere to the existence of life on earth?...

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Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere
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Page 1: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Essential Question: What is the significance of the atmosphere to the existence of life on earth?

pp. 392-407

The Atmosphere

Page 2: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

The Atmosphere

The atmosphere is the layer of gases and other particles that surround earth much like the peel of an apple covers it.

Page 3: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Benefits of atmosphere for humans include:

• provides gases like oxygen

• traps heat energy from sun which keeps us warm and water in a liquid state

• protects from UV rays & most meteoroids

Page 4: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Properties of Air in the Atmosphere

• Air in the atmosphere has density– Air has mass because

it is composed of atoms and molecules

– Air has volume because it takes up space

– density = mass/volume

• Air also has pressure– Air molecules push

on objects from all directions

– As altitude increases air pressure and density decrease because its molecules are spread farther apart

Page 5: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Composition of the Atmosphere • Nitrogen 78%

• Oxygen 21%

• All other gases 1%

• Tiny solid and liquid particles of:

–dust

–smoke

–salt

–chemicals

Page 6: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Structure of the Atmosphere

• Troposphere• Stratosphere• Mesosphere• Thermosphere

–Ionosphere–exosphere

Page 7: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Troposphere

• 0-12 km above Earth’s surface

• Temperature varies– For every 1km of altitude increase, temp decreases

approx 6.5oC – Constant -60oC in upper troposphere

• Where weather occurs and most clouds

• Where hot air balloons travel

Page 8: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Stratosphere

• 12-50 km above Earth’s surface

• Temp in lower stratosphere about -60oC– Warmer in upper stratosphere due to ozone

layer which absorbs ultraviolet radiation

• Where airplanes and weather balloons travel

Page 9: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Mesosphere

• 50-80 km above Earth’s surface

• Temp drops to -90oC in outer mesosphere

• Where most meteoroids burn up– Seen from Earth as shooting stars (meteors)

Page 10: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Thermosphere

• Everything 80km above Earth’s surface

• Temp up to 1,800oC

• Air very thin

• Includes the ionosphere and exosphere

Page 11: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

More on the Thermosphere

Ionosphere• 80-550km above

Earth’s surface• Radio waves

reflected from ionosphere to Earth

• Aurora borealis (Northern Lights) occur in ionosphere

Exosphere• 550km - no limit

above Earth’s surface• Satellites orbit Earth

in the exosphere– Phone signals– Television signals

Page 12: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

Review Questions

a. What significant role does the atmosphere have in providing us with water to drink?

b. Air is invisible, so how does it have density?

c. How does air pressure change as altitude increases? How does density change?

d. Which layer of the atmosphere is the most important to you? Justify you reasons.

Page 13: Essential Question: What is the significance of the atmosphere to the existence of life on earth? pp. 392-407 The Atmosphere.

What is the Atmosphere?

It is the layer of gases that surround the earth.


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