Blizzard

Source: DD News

Context: A severe blizzard struck the eastern face of Mount Everest in Tibet, trapping nearly 1,000 trekkers in the remote Karma valley.

About Blizzard:

What it is?

• A blizzard is a severe mid-latitude snowstorm characterized by strong winds (≥56 km/h), low temperatures, and near-zero visibility caused by blowing snow.

• It occurs when polar or continental cold air masses interact with moist maritime or tropical air, producing intense snowfall accompanied by violent winds.

How It Develops?

• Cold Air Supply: Cold, dense air from high latitudes or elevated terrain ensures snow formation instead of rain.

• Moisture Source: Moist air masses, often from nearby oceans or large lakes, provide water vapour for condensation and precipitation.

• Uplift Mechanism: Warm, moist air is forced to rise over cold air (frontal uplift) or up mountain slopes (orographic uplift), forming snow-laden clouds.

• Strong Pressure Gradient: A steep pressure difference generates high wind speeds, driving snow horizontally and drastically reducing visibility.

Features:

• Wind Velocity: 80–100 km/h (often exceeding 120 km/h in severe cases).

• Temperature: Falls below freezing, intensifying wind chill effects.

• Visibility: Drops below 0.4 km for over three hours, leading to whiteout conditions.

• Duration: Can persist for several hours to days, often followed by cold wave conditions.

• Variants: Ground Blizzard: Pre-existing snow lifted by strong winds. Nor’easter: Coastal blizzard type common along North Atlantic coasts.

• Ground Blizzard: Pre-existing snow lifted by strong winds.

• Nor’easter: Coastal blizzard type common along North Atlantic coasts.

Impact:

• Environmental:

• Causes snow accumulation, avalanches, and temporary glacial expansion. Alters albedo and local energy balance, affecting regional climate feedbacks.

• Causes snow accumulation, avalanches, and temporary glacial expansion.

• Alters albedo and local energy balance, affecting regional climate feedbacks.

• Human:

• Leads to frostbite, hypothermia, and loss of life among trekkers and residents. Transport and communication networks collapse due to snow-blocked roads and damaged power lines.

• Leads to frostbite, hypothermia, and loss of life among trekkers and residents.

• Transport and communication networks collapse due to snow-blocked roads and damaged power lines.