MCQ Detailed View

The Earth’s atmosphere is divided into distinct layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has unique temperature characteristics. Among these, the mesopause is considered the coldest point in the atmosphere.

The mesopause lies between the mesosphere and the thermosphere, at an altitude of about 80–90 kilometers above Earth’s surface. Temperatures here can drop as low as -85°C to -100°C, making it colder than any other atmospheric region.

The reason the mesopause is so cold is due to the low density of air molecules and the balance between incoming solar radiation and outgoing infrared radiation. At this altitude, there are very few gas molecules to absorb and retain heat, causing extreme cooling.

Let’s analyze the options:

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  Tropopause: This is the boundary between the troposphere and the stratosphere (around 10–15 km altitude). It is relatively cold but not the coldest point.

  
  


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  Mesopause: Correct answer. It marks the upper boundary of the mesosphere and is the coldest region in the atmosphere.

  
  


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  Exopause: This is the outermost boundary of the exosphere, where Earth’s atmosphere transitions into outer space. Temperatures here can actually be quite high due to direct solar radiation.

  
  


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  None of these: Incorrect, since mesopause is the scientifically established coldest point.

  
  

The mesopause is also significant in atmospheric studies because noctilucent clouds (very thin, high-altitude clouds that glow after sunset) form in this region. It plays a vital role in understanding upper atmospheric dynamics and the effects of solar activity.

Thus, the correct answer is Mesopause, making it the coldest point in Earth’s atmosphere.