Chapter Overview Lesson 1: The Atmosphere Lesson 2: Weather Elements Lesson 3: Aviation Weather Lesson 4: Weather Forecasting Lesson 5: The Effects of Weather on Aircraft Aircraft Chapter 2, Lesson 1
Lesson Overview Atmospheric regions Roles of water and particulate matter Primary causes of atmospheric motion Identify types of clouds How atmospheric layers impact flight Chapter 2, Lesson 1
Atmospheric Regions Four or five depending on your source material Some consider Exosphere as fifth region extending into space 4 regions extend more than 350 miles from surface Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration
Atmospheric Regions Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration The atmosphere contains the whole mass of air surrounding the Earth Made up of a mixture of gases: 78% Nitrogen (N 2 ) 1% Mixture of other gases (CO 2, pollutants, etc. 21% Oxygen (O 2 ) Atmosphere protects us from high-energy radiation and the frigid vacuum of space Absorbs energy from the Sun, recycles water and other chemicals, and works with the electrical and magnetic forces to provide a moderate temperature
Troposphere Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration Lowest, densest part of Earth’s atmosphere in which most weather occurs Starts at Earth’s surface and extends up to 9 miles Up to 4 miles at poles and 9 miles at equator Tropopause is the boundary layer separating the troposphere and the stratosphere Tropopause and troposphere known as the lower atmosphere
Stratosphere Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration Extends about 30 miles above Earth’s surface Very dry and less dense compared to troposphere Temperature begins to rise again to about 26.6 ⁰ due to ozone layer contained in stratosphere Ozone absorbs Sun’s UV radiation, allowing life to exist on land Stratopause is the boundary layer separating the stratosphere and mesosphere
Mesosphere Chapter 2, Lesson 1 Courtesy of NASA Extends up to 53 miles above Earth’s surface Coldest layer – near top of mesosphere, temps dip to as low as -93 o C (-135 o F) Chemicals exist in an excited state by absorbing energy from Sun Mesopause separates mesosphere from thermospere Mesosphere and stratosphere form middle atmosphere
Thermosphere Thermosphere —Exosphere Extends about 350 miles above Earth’s surface Considered the “hottest” layer as it absorbs direct energy from the sun first Chemical reactions occur faster here than on Earth’s surface Molecular temps can reach over 3000⁰ F But actual energy per volume is low since thermosphere is practically a vacuum Most satellites and spacecraft orbit in this layer Thermopause is the boundary layer with exosphere Chapter 2, Lesson 1
Roles of Water and Particulate Matter Chapter 2, Lesson 1
Roles of Water and Particulate Matter Chapter 2, Lesson 1 The water content of the atmosphere is almost entirely restricted to the troposphere. Occasionally, a thunderstorm will produce enough energy to thrust part of its top into the stratosphere. Water may also be injected into the stratosphere by the engines of high-flying aircraft.
Roles of Water and Particulate Matter Chapter 2, Lesson 1 In the troposphere, water goes through a cycle from water vapor to condensation to precipitation As it goes through this cycle, it takes on several forms. Liquid Solid Condensation
Evaporation: liquid to gaseous Sublimation: solid to gaseous without first going through liquid state Condensation: gaseous to liquid Deposition: gaseous to solid without first going through liquid state Melting: solid to liquid Freezing: liquid to solid Chapter 2, Lesson 1 Roles of Water and Particulate Matter
Evaporation Chapter 2, Lesson 1 Courtesy of NOAA/Historic NWS Collection The process by which liquid water molecules change to a gas or vapor state and enter the atmosphere Evaporation requires heat 86% of evaporation occurs from solar radiation heating the oceans creating water vapor Clouds form when air is saturated with water vapor Temperature and pressure are the primary cause of water vapor in the air condensing into liquid (forming clouds) then falling to Earth
Sublimation Ever notice how old ice cubes in the freezer become smaller and deformed? Ever notice how a snowbank seems to get smaller or disappear even though temps were below freezing? Sublimation occurs in below freezing temps Intense sunlight with strong winds can transform snow and ice into water vapor without first melting Chapter 2, Lesson 1 Courtesy of NASA/Goddard/Sarah DeWitt
Humidity and Relative Humidity Humidity (or absolute humidity) is the actual amount of water vapor in air at a given time The amount of water vapor the air is able to hold depends on the temperature Higher temps => hold more water vapor Relative humidity - Amount of water vapor that can still enter the air mass before it becomes saturated Expressed as ratio of the absolute humidity to the maximum amount of water vapor that air could hold at that given temperature and pressure Chapter 2, Lesson 1
Humidity and Relative Humidity Chapter 2, Lesson 1
Condensation and Precipitation Chapter 2, Lesson 1 Courtesy of NASA/Ben Smegelsky When air become saturated, any more water vapor added will return to a liquid or solid form Seen as either condensation and/or precipitation If a cloud’s droplets grow until the buoyancy of the air and any existing updrafts will not support them, they fall as precipitation
Condensation and Precipitation Chapter 2, Lesson 1 Courtesy of NASA/Ben Smegelsky If the water vapors that fall are not visible, it is condensation
Dew Point Temperature at or below which water vapor in air will condense Determined by the amount of moisture in the air and the air temperature Does not indicate the type of condensation, only that some type of condensation will take place at the dew point Could be fog, dew, frost, clouds, rain, hail, snow, etc Chapter 2, Lesson 1 Courtesy of NASA/Ben Smegelsky
Particulate Matter Dust, pollution and other small particles play an important role in the water cycle Without suspended particles in the atmosphere, certain forms of condensation and precipitation would not exist These particles serve as condensation nuclei for water vapor when the temp is right This is how cloud droplets form Chapter 2, Lesson 1 Courtesy of Sean Waugh NOAA/NSSL
Primary Causes of Atmospheric Motion Heat causes air to circulate around Earth’s surface Rising warm air and heavy, sinking cool air results in atmosphere’s circular motion Tilted axis also affects atmospheric circulation Chapter 2, Lesson 1 Modified from US Department of Transportation/Federal Aviation Administration.
Coriolis Force How Earth’s rotation affects the motion of air Deflects air to the right in Northern Hemisphere and left in Southern Hemisphere Breaks up flow of air into three cells at different latitudes in each hemisphere Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration
Chapter 2, Lesson 1 Reproduced from US Department of Transportation/Federal Aviation Administration The Atmosphere Part 1 of 2 Done….. next….Part 2 of 2
Your consent to our cookies if you continue to use this website.