Published on 31 Jan 2025
Embedded in the upper tropospheric westerlies, at the interface of Hadley, Ferrel and Polar cells, there are bands of swift moving winds known as jet streams. They follow a meandering path.
Characteristics of jet streams
Formation: Jetstream are primarily a result of the temperature contrast between equatorial and Polar Regions. The Coriolis Effect, caused by the Earth's rotation, also influences their formation.
Rotation: Circulation of Jet streams is from west to east due to the effect of Earth rotation. Generally, the circulation is observed between poles and 20 degrees latitude in both the hemispheres.
Speed: The average wind speed is very high with a lower limit of about 120 km per hour in winter and 50 km per hour in summer.
Influencing monsoons: The periodic movement of the Jet Stream often indicates the onset and subsequent withdrawal of the monsoon.
Permanent and seasonal: Polar jet streams and Sub-tropical westerly Jetstream are called permanent Jetstream whereas tropical easterly Jetstream is a seasonal Jetstream.
Types of jet streams
Sub-tropical westerly Jetstream: Formed between Hadley and Ferrel cells. Subtropical westerly jet stream flows from west to east, following the general westerly flow pattern of the mid-latitude atmospheric circulation.
Influence on weather: Brings light rainfall over northern India during winter by capturing temperate cyclones in the form of western disturbances.
Polar Jetstream: Formed between Ferrel and Polar cells. The polar jet stream is located at high latitudes, typically around 50° to 60° N and S in the Northern and Southern Hemispheres, respectively.
Influence on Weather: The polar jet stream plays a crucial role in steering weather systems and fronts. It influences the development and movement of low-pressure systems, cyclones, and storms.
Significance of jet streams
Weather patterns: The jet stream marks air mass boundaries, shaping weather globally. Its meandering influences high and low-pressure systems, impacting regional weather conditions.
Storm development: Crucial for cyclone formation, the jet stream's interaction with atmospheric features intensifies storms, affecting weather dynamics.
Aviation: Vital for flight planning, the jet stream's strong winds either assist or hinder aircraft, influencing routes and travel times for improved fuel efficiency
Climate patterns: Jet stream variations, linked to phenomena like El Niño, impact long-term climate, shaping regional and global weather conditions.
Temperature regulation: By redistributing heat from the equator to the poles, the jet stream helps maintain Earth's energy balance, influencing seasonal temperature variations.
Weather forecasting: Meteorologists use jet stream data to enhance forecasts, predicting weather systems' development, including storms and precipitation events, for improved preparedness and planning.
Connection between jet streams and Indian climate
Winter season influence: During the winter season, the subtropical jet stream flows from west to east, influencing the climate over India. It brings cool and dry air from the west, affecting the weather patterns, especially in northern and central India.
Westerlies and cyclonic activity: The jet stream guides westerly winds, influencing cyclonic systems during pre-monsoon and post-monsoon seasons.
Monsoon dynamics: The jet stream's position affects the onset and withdrawal of the Indian monsoon, allowing the seasonal rainfall.
Impact on weather systems: Jet stream influences the behavior of weather systems like western disturbances, bringing rain and snow to northern India in winter.
Geography
Jetstream
Characteristics of jet streams
Types of jet streams
Sub-tropical westerly Jetstream
Polar Jetstream
Significance of jet streams
Connection between jet streams and Indian climate
General Studies Paper 1
Physical Geography
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