Atmosphere and Waves A Mc GourtyRideout Tutorial Layers
- Slides: 37
Atmosphere and Waves A Mc. Gourty-Rideout Tutorial
Layers of the Atmosphere
The Troposphere • Most dense • All weather takes place here
The Stratosphere • • Dry Absorbs ultraviolet radiation (UV) Ozone layer is here Ozone (O 3) absorbs much UV C and UV B waves.
The Mesosphere • Coldest • Many meteors burn up here
The Ionosphere • Region of charged ions (positive) and electrons • Electrons are torn off atoms by sunlight of short wavelengths • Electrons don’t recombine easily because the distance between molecules is large at high altitudes and collisions are not frequent
How Far Does the Atmosphere Extend? images are courtesy of Windows to the Universe, http: //www. windows. ucar. edu
Which waves on the EM spectrum get through to us on Earth?
Visible Light and some Infrared get through But that’s NOT all!!! images are courtesy of Windows to the Universe, http: //www. windows. ucar. edu
So Do Radio Waves!!!!!
Troposphere – Most radio waves are refracted – Short wavelength-absorbed
Attenuation by the troposphere • All wavelengths >25 cm pass through • O 2, H 2 O, and weather ( rain, fog, etc) cause attenuation
Refraction in the troposphere • nair= 1. 00029 when T=0°C and P=760 mm of Hg • “n” differs for light and radio waves only due to presence of water vapor which increases dielectric constant
As a ray moves from one layer of the atmosphere to another it bends
The Ionosphere Can Cause Reflection • The ionosphere is known to reflect most radio waves because of its ions and free electrons
Penetration and Refraction • Penetration and refraction- dependent on electron density and wave frequency
Radio Ga-Ga • The ionosphere refracts radio waves of certain frequencies ( 3 -30 MHz or short waves) • This refraction makes worldwide radio communication possible without using satellites
Refraction in the ionosphere • Larger than tropospheric • Refraction at lower frequencies <40 MHz • Wedge refraction- east-west electron density gradients due to local solar time- cause ionosphere to act like tiny prism
Attenuation by the Ionosphere • Ionization varies with latitude, season, solar time, and phase of sunspot cycle • 2 regions- E and F where penetration take place • Region D- absorption • Divergence occurs at angles of incidence<30° and intensity on ground is reduced • Absorption loss increases with air densitygreatest in lower ionosphere
Check out the ionosphere and the role its layers play in radio wave communication in this really cool video.
Still don’t get it, then move onto the next slide. If not click here:
Layers of the Ionosphere • Lowest part: D layer has enough collisions to cause it to disappear after sunset • Remaining ions and electrons recombine, without sunlight new ones are no longer produced • Layer return at sunrise
D Layer and Radio Transmission • Low frequencies ( below 10 MHz) absorbed - high frequencies pass through • More ionized = more radio wave absorption • Maximum usable frequency ( highest frequency that can be refracted) : 16 MHz • Optimal usable frequency: 13. 6 MHz • Most abundant molecule present: O 3
E Layer of Ionosphere • Ionized gas • Reflects medium frequency waves, causes radio waves to be propagated beyond horizon • Day- solar wind presses this layer closer to the Earth limiting distance radio waves can be reflected • Night - solar wind drags the ionosphere further away, increasing the range of radio waves • Season and sunspot activity also influence reflection
E Layer and Radio Transmission • Refracts radio signals and causes them to skip back to earth • Weakest at night - radio signals pass right through • Maximum usable frequency : 28 MHz • Optimal usable frequency : 23. 8 MHz • Most abundant molecule: O 2 • Few seasonal or daily differences for transmission
F Layer of Ionosphere • Most important in terms of high frequency communications • During the day- 2 layers; combines into one layer at night • Thickest • Most reflective of radio on the side of the Earth facing the sun
F Layer and Radio Transmission • Ionized all night • Refracts higher frequencies by day, but passes them through at night • Low frequencies ( 10 -15 MHz) are refracted back to earth at night • Maximum usable frequency : 16 MHz • Optimal usable frequency : 13. 6 MHz • Most abundant molecules present: Nitrogen in F 1 sub layer and Oxygen in F 2 sub layer.
Radio Waves Through the Atmosphere • D layer disappears at night- low frequencies can now be used ( AM vs. FM) • E Layer weak at night • F sublayers combine into one layer at night • Sunspots can increase the ionosphere’s ability to refract high frequency radio waves • Solar flares can increase the amount of radio wave absorption, thus hurting radio communications
Space Weather • What happens in the Sun and in space effects what happens here on Earth. To find out more click
What Else Can the Sun Do? • The Earth has a magnetic field that reaches into space • The magnetic field of the Earth is surrounded in a region called the magnetosphere. The magnetosphere prevents most of the particles from the sun ( solar wind) from hitting the Earth • Some particles from the solar wind can enter the magnetosphere and cause auroras
Earth’s Magnetic Field
Solar Wind Coming Towards Earth’s Magnetosphere- watch the video
Radio Waves Paths the images are courtesy of Windows to the Universe, http: //www. windows. ucar. edu
Ionosphere , Plasma, and Communication
Radio window to the universe • Extends from. 5 mm to 10 m • <3 cm water vapor absorbs incoming radio emissions • Between 3 cm-50 cm atmospheric conditions don’t effect observations • >50 cm ionosphere and solar activity play crucial role in observations- night observations are best • Any electrical devices between the 3 cm-50 cm band can effect observations- microwaves, garage door openers, cell phones, and remote controls due to harmonics
- Lowest level of earth's atmosphere
- Compare and contrast p waves and s waves using venn diagram
- Layers of the atmosphere song
- Study jams layers of the earth
- Scientists divide the atmosphere into how many layers?
- Earth's atmosphere description
- Layers of the atmosphere song
- Thermosphere layer
- 1st layer of atmosphere
- Layers of the atmosphere
- The four main layers of the atmosphere
- Differences between mechanical and electromagnetic waves
- Example of a mechanical wave
- Difference between electromagnetic waves and sound waves
- What is a semiconductor used for
- Difference between matter waves and electromagnetic waves
- Mechanical and electromagnetic waves similarities
- Seismic waves
- What do all waves transmit
- What are constructive waves
- Light is electromagnetic radiation true or false
- What type of waves are sound waves? *
- Sound is a longitudinal wave
- Mechanical waves vs electromagnetic waves
- Seismic waves are mechanical waves
- Hydrosphere
- Earth systems
- Chapter 13 atmosphere and climate change section 1
- The setting of the necklace
- Describe two ways nick differs other guests party
- Setting is the time and place
- Chapter 13 atmosphere and climate change
- Troposphere facts
- Atmosphere ideas
- 5 oceans
- Ocean atmosphere and climate
- Solar energy and the atmosphere
- Which sphere of earth includes icebergs?