High Altitude Sciences: The Ozonosphere, Mesospheric Cold, Ionosphere, and Van Allen Belts
Continuing our ascent into Earth's upper atmosphere, we encounter three remarkable atmospheric layers. Above the tropopause lies the 'Stratosphere' (13 to 50 km), home to the life-protecting ozone layer; its air moves horizontally and is free from storms, making its lower portion ideal for passenger aircraft navigation. Next is the 'Mesosphere' (50 to 85 km), the coldest layer in the atmosphere (-90°C), where celestial rock debris burns due to friction to form glowing meteors. Finally, the 'Thermosphere' (the thermal layer) extends up to 675 km, with temperatures reaching a scorching 1200°C. Its upper electrified region, the 'Ionosphere', reflects high-frequency radio waves and is encircled by the magnetic 'Van Allen Radiation Belts', which deflect hazardous cosmic rays to create the mesmerizing Aurora displays at Earth's poles.
1. The Stratosphere (Ozonosphere)
Properties of the second atmospheric layer:
- Altitude: Extends from the tropopause (13 km) to the stratopause (50 km), thickness ~37 km.
- Ozone Layer: Concentrated between 20 and 40 km above sea level.
- Temperature Inversion: Starts at -60 °C in its lower part and rises gradually to 0 °C at the stratopause due to the absorption of solar ultraviolet (UV) radiation by ozone molecules.
- Aviation Advantage: Air moves horizontally, devoid of clouds and turbulence, providing a tranquil highway for jet planes.
2. Mesosphere, Thermosphere & Ionosphere
Coldest layer, hottest layer, and magnetic shields:
- Mesosphere (Middle Layer): Extends 50 to 85 km. Coldest layer (-90 °C at mesopause). Highly rarefied; friction with gas particles burns space rocks to form meteors.
- Thermosphere (Thermal Layer): Extends up to 675 km. Hottest layer (reaches 1200 °C).
- Ionosphere & Van Allen Belts:
• Contains charged ions extending to 700 km; reflects radio waves for global telecommunications.
• Encircled by two magnetic belts (Van Allen belts) that deflect cosmic radiation, creating the Aurora (Northern Lights).
• Followed by the Exosphere, where communications satellites orbit.
Conceptual Science Clinic:
Answer: Because it is completely free from clouds, weather disturbances, and storms, and its air currents circulate horizontally rather than vertically.
Answer: 1. Deflecting harmful charged cosmic radiation away from Earth. 2. Producing the colorful Aurora light displays at the North and South magnetic poles.
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