Daily News Analysis

Noctilucent Clouds

stylish_lining

The recent sightings of noctilucent clouds from parts of Scotland are a beautiful natural phenomenon that can be both scientifically intriguing and visually stunning.

What Are Noctilucent Clouds?

  • Appearance:
    Noctilucent clouds are thin, wispy clouds that glow with a
    blue or silvery hue at night. The glow is caused by sunlight illuminating the clouds from below the horizon, even when the rest of the surface is in darkness. This makes them appear to "shine" brightly in the night sky.

  • Location in the Atmosphere:
    Unlike most clouds that form in the
    troposphere, noctilucent clouds are found in the mesosphere, the third layer of Earth's atmosphere. This makes them the highest clouds in the Earth's atmosphere, typically occurring at altitudes between 76 km to 85 km (47 to 53 miles).

  • Formation:
    These clouds are primarily made of
    ice crystals. During the summer months, the mesosphere cools enough for ice to form on dust particles suspended in the atmosphere. The dust particles may come from micrometeorites falling from space, remnants of volcanic eruptions, or even human activity such as rocket exhaust.

  • Unique Characteristics:
    The name
    noctilucent comes from the Latin words nocto (night) and lucent (shining), reflecting how they appear to "shine" at night. They are often referred to as polar mesospheric clouds because they are typically visible at latitudes between 45 and 80 degrees north or south of the equator.

When and Where Do Noctilucent Clouds Appear?

  • Seasonal Timing:
    Noctilucent clouds are primarily a
    summer phenomenon. In the Northern Hemisphere, they can be seen from the end of May to early August, with sightings being most frequent in June and July. In the Southern Hemisphere, sightings are rarer, but they can occur from November to February, peaking in December and January.

  • Why Summer?
    The mesosphere cools during summer, allowing the ice crystals to form on suspended particles. The long days and extended twilight at these latitudes make it possible for sunlight to reach these high-altitude clouds at night, causing them to glow. The further north you go, the longer the period of twilight, and thus the longer the potential for noctilucent clouds to be visible.

Formation Process

Noctilucent clouds are primarily composed of ice crystals.

  1. Cooler Temperatures in the Mesosphere:
    During summer, the
    mesosphere experiences cooler temperatures, allowing water vapor to freeze into ice crystals.

  2. Suspended Dust Particles:
    These ice crystals form on
    dust particles, which can originate from:

    • Micrometeorites: Tiny fragments of space debris entering Earth's atmosphere.

    • Volcanic Eruptions: Ash and particles from volcanoes can travel into the upper atmosphere and become part of the clouds.

    • Human Activities: Rocket launches can also introduce particles into the mesosphere, which may seed the formation of noctilucent clouds.

  3. Reflection of Sunlight:
    The ice crystals reflect sunlight, especially when the Sun is just below the horizon. This causes the clouds to glow with a
    bluish-silver color during the night.

Noctilucent clouds are valuable for climate and atmospheric research. Their formation is sensitive to temperature and atmospheric composition, so studying them can help scientists understand changes in the mesosphere and climate patterns. They also serve as indicators of changes in the upper atmosphere.


 

Collegium System of Judicial Appointments in India

The Collegium system refers to India's judicial process for appointing and transferring judges to the Supreme Court and High Courts. While the system plays a crucial role in maintaining judici
Share It

Sea-Level Rise

Coral micro-atolls are essential natural recorders of sea-level rise (SLR), offering valuable insights into past and present oceanic changes. These disk-shaped coral colonies provide a unique meth
Share It

India’s Strategy in the Indian Ocean

Why the Indian Ocean Matters: Strategic Importance: The Indian Ocean is the third-largest ocean in the world, hosting 1/3rd of the global population and acting as a crucial maritime trade
Share It

ASEAN Centrality

Why in the News? ASEAN’s central role in the Indo-Pacific is increasingly under strain due to rising great-power rivalry, shifting global trade dynamics, and the evolving regional order.
Share It

2025 SCO Summit in Tianjin

The 25th Shanghai Cooperation Organization (SCO) Summit held in Tianjin, China in 2025 brought together the heads of state of member countries to address a broad spectrum of issues, including secu
Share It

India’s Carbon Emissions Trading System

The Ministry of Environment, Forest and Climate Change (MoEFCC) has made a significant stride in India’s climate strategy by setting up the National Designated Authority (NDA) to implement a
Share It

Jan Vishwas (Amendment of Provisions) Bill, 2025

The Jan Vishwas (Amendment of Provisions) Bill, 2025 was introduced in the Lok Sabha to amend various provisions across several central acts with the goal of decriminalizing offences and promoting
Share It

Fair and Representative Global Order

India’s External Affairs Minister recently called for a fair and representative global order during the BIMSTEC Traditional Music Festival. The statement highlights the growing need for reforms
Share It

India's First EMI-Based Credit Card

Recently, Unity Small Finance Bank and BharatPe launched India's first EMI-driven credit card on the RuPay network. This innovative product allows users to pay for their purchases in full or c
Share It

Civil Society Organizations (CSOs)

Why in News? Civil Society Organizations (CSOs) have gained prominence for their vital role in promoting collective action, protecting rights, and filling gaps in governance. They serve as cata
Share It

Newsletter Subscription


ACQ IAS
ACQ IAS