The Sun and the Earth's Atmosphere
The Sun's Energy and Its Importance
1
Providing Light
It allows plants to grow through photosynthesis, which produces oxygen and food.
2
Warming the Earth
The Sun's heat maintains a suitable temperature for living organisms.
3
Driving Weather and Climate
Solar energy influences wind patterns, ocean currents, and the water cycle.
Layers of the Earth's Atmosphere
1
Exosphere
Outermost layer
2
Thermosphere
Aurora lights occur
3
Mesosphere
Meteors burn up
4
Stratosphere
Contains ozone layer
5
Troposphere
Weather occurs
The Atmosphere of Earth
The Earth's Atmosphere surrounds our planet and is mostly composed of air. The atmosphere is essential to living things - it provides carbon dioxide for plants and oxygen for animals.
The two main gases that make up the atmosphere are nitrogen (approximately 78%), and oxygen (approximately 21%). Argon and traces of other gases, such as carbon dioxide, make up the rest. The total water content in the atmosphere is about 0.25%, mostly made up of water vapor.
Composition of Earth's Atmosphere
Nitrogen
Oxygen
Argon
Carbon Dioxide
Other Gases
The Troposphere
Altitude
Extends up to about 13 kilometers (km) from the Earth's surface.
Mass
This layer holds 75% of the atmosphere's mass.
Temperature
As you go higher, the temperature drops from an average of about 13°C near the Earth's surface to -50°C at the top of the layer.
Air Pressure
The air pressure drops from 1000 millibars (mb) near the Earth's surface to 100 mb at the top of the layer.
The Stratosphere
Ozone Layer
Contains the ozone layer, which absorbs harmful ultraviolet (UV) rays from the Sun.
Altitude
Extends from about 13km to 48km above the Earth's surface.
Temperature
The temperature of the bottom of the layer is -50°C but at the top, its temperature is -15°C.
Air Pressure
The air pressure at the bottom of the layer is about 100 mb but at the top of the layer, the air pressure is only 1 mb.
The Mesosphere
1
Location
This layer lies directly above the stratosphere.
2
Altitude
It extends from about 48 km to 85 km above the Earth's surface.
3
Temperature
The temperature of the bottom of the layer is -30°C but at the top, it is only -90°C.
4
Air Pressure
The air pressure at the bottom of the layer is about 1 mb but at the top of the layer, the air pressure is only 0.01 mb.
The Thermosphere
Location
This layer lies directly above the mesosphere.
Altitude
It extends from about 85 km to 700 km above the Earth's surface.
Temperature
The temperature of the bottom of the layer is -90°C but at the top of the thermosphere it can be 350°C or higher.
Air Pressure
The air pressure at the bottom of the layer is about 0.01 mb but at the top of the layer the air pressure is very weak at about 0.000001 mb.
The Exosphere
Location
This layer is the uppermost layer of Earth's atmosphere.
Altitude
It extends 10,000 km into space.
Characteristics
It blends with what scientists consider to be outer space!
Gravity Effects
The pull of Earth's gravity is so small in this layer that molecules of gas escape into outer space.
Temperature Variations in Atmospheric Layers
Altitude (km)
Temperature (°C)
Air Pressure in Atmospheric Layers
Pressure at Bottom (mb)
Pressure at Top (mb)
Solar Energy and the Atmosphere
Sun Emits Energy
The Sun radiates energy in all directions
1
Energy Travels to Earth
Takes 8⅓ minutes to reach Earth
2
Atmosphere Filters Radiation
Different layers absorb different wavelengths
3
Earth Receives Filtered Energy
Safe levels reach the surface
4
Fun Fact: Solar Energy Travel Time
On average, it takes approximately 8 1⁄3 minutes or 500 seconds for solar energy to reach the top of Earth's atmosphere. Covering an approximate distance of 149 million kilometers through space, this energy reaches the top layer of Earth's atmosphere. Solar energy propagates in waves from the Sun, traveling at the speed of light as electromagnetic radiation within the vacuum of space.
Types of Solar Radiation
Ultraviolet (UV) Radiation
High-energy radiation that can damage skin and eyes. Most is absorbed by the ozone layer in the stratosphere.
Visible Light
The radiation we can see with our eyes. Most passes through the atmosphere to reach Earth's surface.
Infrared Radiation
Felt as heat. Some is absorbed by greenhouse gases in the troposphere, helping to warm the Earth.
The Greenhouse Effect
1
Solar Radiation Enters
Sunlight passes through the atmosphere
2
Earth Absorbs Energy
Surface warms and emits infrared radiation
3
Greenhouse Gases Trap Heat
CO₂, methane, water vapor capture heat
4
Earth Maintains Temperature
Heat balance allows life to flourish
Clouds and the Atmosphere
Clouds play an important role in Earth's atmosphere and weather systems. They form when water vapor in the air condenses into visible water droplets or ice crystals. Different types of clouds form at different altitudes and have distinct characteristics.
Types of Clouds by Altitude
Cloud Types and Characteristics
Cloud Type
Altitude
Appearance
Weather Association
Cirrus
High
Thin, wispy
Fair weather
Cumulus
Low
Puffy, cotton-like
Fair weather
Stratus
Low
Flat, gray layer
Drizzle
Cumulonimbus
Vertical
Tall, anvil-topped
Thunderstorms
Nimbostratus
Low to middle
Dark, gray layer
Continuous rain
The Ozone Layer
15-35
Altitude (km)
The ozone layer is located in the stratosphere at this height above Earth's surface.
90%
UV Protection
The ozone layer absorbs this percentage of the Sun's harmful ultraviolet radiation.
3
Oxygen Atoms
Ozone (O₃) consists of three oxygen atoms, unlike the oxygen we breathe (O₂).
Interaction of Solar Energy with Atmospheric Layers
Exosphere
First contact with solar radiation; some high-energy particles are deflected by Earth's magnetic field.
Thermosphere
Absorbs X-rays and extreme UV radiation, causing molecules to become ionized.
Mesosphere
Meteors burn up here due to friction with air molecules; absorbs some UV radiation.
Stratosphere
Ozone layer absorbs most of the remaining harmful UV radiation.
Troposphere
Greenhouse gases trap infrared radiation, warming the Earth's surface.
The Importance of the Atmosphere for Life
Provides Oxygen
The atmosphere contains the oxygen that animals need to breathe.
1
Provides Carbon Dioxide
Plants use carbon dioxide from the atmosphere for photosynthesis.
2
Regulates Temperature
The greenhouse effect keeps Earth warm enough for life.
3
Blocks Harmful Radiation
The ozone layer and other parts of the atmosphere protect life from harmful solar radiation.
4
Enables Weather
The atmosphere's movement creates weather patterns that distribute water and nutrients.
5
Atmospheric Pressure and Altitude
Altitude (km)
Pressure (mb)
Atmospheric Vocabulary
Exosphere
From Greek "exo" meaning "outside" + "sphere" - the outermost layer of Earth's atmosphere.
Thermosphere
From Greek "thermos" meaning "heat" + "sphere" - the layer where temperature increases with altitude.
Mesosphere
From Greek "mesos" meaning "middle" + "sphere" - the middle layer of Earth's atmosphere.
Stratosphere
From Greek "stratum" meaning "layer" + "sphere" - a layered region of the atmosphere.
Troposphere
From Greek "tropos" meaning "changes" + "sphere" - the layer where weather changes occur.
Self-Assessment: Understanding the Atmosphere
Red Light
I don't understand this concept yet and need more help.
Yellow Light
I partially understand this concept but still have some questions.
Green Light
I understand this concept well and can explain it to others.
Evaluating Your Knowledge
1
Question 1
What is the main source of energy for the Earth?
2
Question 2
Which layer of the atmosphere contains the ozone layer that protects us from harmful ultraviolet rays?
3
Question 3
What process allows the Earth's atmosphere to trap heat and maintain a suitable temperature for life?
4
Question 4
In which layer of the atmosphere do weather patterns occur?
5
Question 5
What would happen if the ozone layer were destroyed?
Answer Key
Question 1
B) The Sun
Question 2
B) Stratosphere
Question 3
B) Greenhouse Effect
Question 4
C) Troposphere
Question 5
A) The Earth would receive more harmful UV rays.
Additional Activities: Fill in the Blanks
Question 1
The Sun is the primary source of _______ for the Earth.
Question 2
The _______ protects us from harmful ultraviolet (UV) rays from the Sun.
Question 3
The lowest layer of the atmosphere, where weather occurs, is called the _______.
Question 4
The _______ is responsible for burning up meteors before they reach the Earth's surface.
Question 5
Excessive _______ in the atmosphere contributes to global warming.
Short Answer Questions
1
Question 6
Why is the Sun important for life on Earth?
2
Question 7
How does the atmosphere protect us from the Sun's harmful effects?
3
Question 8
What is the greenhouse effect, and how does it help the Earth?
4
Question 9
What are some human activities that negatively affect the Earth's atmosphere?
5
Question 10
What can we do to protect the atmosphere and reduce global warming?
Learning Resources