Chapter 7: The Atmosphere

Annotations:

• Composition of the Atmosphere:  Nitrogen: Most common gas Oxygen: Second most found gas Carbon Dioxide: Needed for life. Other gases: These are called trace gases because there are very little of them. Water Vapor: It is important to Earth's weather because it causes rain, snow, and ice. Particles: Air is also made up from tiny solid and liquid particles of dust, smoke, salt, and other chemicals.
• The Earth's atmosphere is very important because it makes conditions on Earth suitable for us to live. The air we breathe isn't completely healthy. Pollutants, harmful substances in the air, soil, or water, are what make it unhealthy. Some pollution is natural, caused by fires, volcanoes, etc. The burning of fossil fuels causes smog and acid rain, man-made pollution.

Annotations:

• Properties of Air: Density: Density is the amount of mass in a given volume of air.  Pressure: Pressure is the force pushing on an area or surface.
• Measuring Air Pressure: Barometers are used to measure air pressure.  Mercury Barometers consist of a glass tube open at the bottom and partially filled with mercury. Aneroid Barometers have airtight metal chambers.
• Altitude and the Properties of Air: Altitude affects Air Pressure: Air near the top of the atmosphere has less weight pressing on it, which means there is less air pressure. Altitude also Affects Density: The higher through the atmosphere you go, the density of the air decreases.   

Annotations:

• The Troposphere: The troposphere is the layer of Earth's atmosphere in which weather occurs. Air pressure decreases as you go through the atmosphere. As altitude increases, the temperature decreases.
• The Stratosphere: The stratosphere is the second layer of the atmosphere and contains the ozone layer. The lower stratosphere is cold, but the upper part is warmer. The higher you go, the more the air pressure decreases. The volume of a hot air balloon would increase.
• The Mesosphere: The mesosphere is the layer of the atmosphere that protects Earth from being hit by most meteoroids.
• The Thermosphere: This layer is the outermost layer of the atmosphere. Even though it is very thin, it is still very hot since sunlight hits it first. Nitrogen and oxygen molecules turn this energy into heat. The thermosphere has two layers. The lower layer is called the ionsphere, while the outer portion is called the exosphere.  

Annotations:

• Energy from the Sun: Most of the energy from the sun travels to Earth in the form of visible light. Visible Light: Visible light comes in all the colors of the rainbow. The different colors are the result of different wavelengths. Non-visible Radiation: Infrared radiation has wavelengths longer than red light. Ultraviolet radiation, which is an invisible form of energy, has wavelengths shorter than violet light.
• Energy in the Atmosphere: Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface. The rest passes through the atmosphere to the surface. Scattering is a process in which dust particles and gases in the atmosphere reflect light in all directions.
• Energy in Earth's Surface: When Earth's surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation. It is absorbed by gases in the air. The gases form a "blanket" in the air that holds heat in the atmosphere. The greenhouse effect is the process in which gases hold heat in the air.

Annotations:

• Thermal Energy and Temperature:  Measuring Temperature: Air temperature is measured with a thermometer.  Temperature Scales:   Temperature is measured in degrees. The two common scales are the Fahrenheit and Celsius scales.   
• How Heat is Transferred:  Radiation: Radiation is the direct transfer of energy by electromagnetic waves. Conduction: The direct transfer of heat from one object to another it is touching is called conduction. Convection: Convection is the transfer of heat by the movement of a fluid. Heating the Troposphere: In the troposphere, heat is mostly transferred by convection. Convection currents, upward movements of warm air and the downward movement of cool air, move heat through the troposphere. 

Annotations:

• What is Wind: Winds are caused by differences in air pressure. 
• Local Winds: Local winds are winds that blow over short distances.  Sea Breeze: A sea breeze is a local wind that blows from a body of water. Land Breeze: The flow of air from land to a body of water is called a land breeze 
• Global Winds: Global winds are winds that blow steadily from specific directions over long distances.  Global Convection Currents: Air pressure tends to be lower at the equator and higher at the poles. The difference in pressure causes winds at Earth's surface to blow from the poles toward the equator. The Coriolis Effect: The way Earth's rotation makes winds curve is the Coriolis effect. Because of the Coriolis effect, global winds in the Northern Hemisphere gradually turn toward the right. 
• Global Wind Belts: The major global wind belts are the polar easterlies, the trade winds, and the prevailing westerlies. Doldrums: Regions near the equator with little or no wind are called doldrums. Horse latitudes: Latitude is distance from the equator, measured in degrees. The latitudes 30 degrees north and south of the equator came to be called the horse latitudes.
• Trade Winds: Winds in the Northern Hemisphere between 30 degrees north latitude and the equator generally blow from the northeast. Same for the Southern Hemisphere, but 30 degrees south latitude and the winds blow from the southeast.
• Prevailing Westerlies: In the mid-latitudes, between 30 and 60 degrees north and south, winds that blow toward the poles are turned toward the east by the Coriolis effect. Since they blow from the west to the east, they are called the prevailing westerlies.
• Polar Easterlies: The Coriolis effect shifts these polar winds to the west, producing the polar easterlies.  Jet Streams: Jet streams are bands of high-speed winds. As jet streams travel around Earth, they wander north and south in a wavy path.