Question – Presenting the distribution of impact of dust storms, mention the reasons for the increasing frequency of dust storms observed in the last few years. – 28 July 2021
Answer –
- In 2018, there have been 50 dust storm events in 16 states of India, causing more than 500 deaths. In comparison, there were 22 thunderstorms between 2003 and 2017, compared to only nine between 1980 and 2003.
Where do dust storms most commonly occur?
- Dust storms are formed due to the combination of dust and strong winds. North Africa, the Arabian Peninsula, Iran, India, Afghanistan, Pakistan and China experience the most dust or sand storms. Dust storms also occur in other arid regions such as the Atacama Desert, west and central Australia, and North America.
What are the causes of widespread dust storm in India?
- The changing nature of Western Disturbances is a major factor in widespread dust storms in India.
- It is a type of tropical storm that originates from the Mediterranean region and causes rain in the winter season in North India. Basically, this storm passes through the Black Sea and the Caspian Sea and reaches India carrying a lot of moisture. Due to low air pressure in summer, strong winds blow in the lower layer of the atmosphere and these storms leave over the Himalayas. But in winter when the air pressure is high, these storms pass under the Himalayas and cause rain in the north-western part of India. In this way, these winds coming from the west, which change the weather of our country for some time, are called Western Disturbances.
What’s new in western disturbances this year?
- Western Disturbances are changing due to the warming in the Arctic. In the first year two-three western disturbances were normal, but now their number has increased to ten and more. Moreover, their arrival time is also getting delayed. Generally, Western Disturbances used to come in the winter season, due to which snowfall occurred but now they are coming from April to May and June also. This is a new and changed character of Western Disturbances.
- As the Arctic warms, the temperature difference between this cold region and the equator has narrowed. Due to which the flow of the jet stream-wind flowing in the middle of the Arctic equator has weakened. Along with this, instead of flowing straight ahead on its path, it is wandering here and there on an undetermined path, due to which the weather and flow of Western Disturbance is changing.
Is western disturbance the only factor responsible for the extreme nature of these dust storms?
- The fact is that the temperature is increasing continuously in the Bay of Bengal where the average normal temperature has increased by 1 to 2 degree Celsius. Which means more moisture is available for the movement of cyclones. This cyclonic system is now leading to intense and widespread storms as it collides with a dry, cold but late Western Disturbance. An increase in temperature has been recorded for the entire northern subcontinent this year. Rajasthan recorded an average temperature of 46 degrees Celsius at the end of April, while the mercury crossed 50 degrees Celsius in Pakistan, which is 4-5 degrees Celsius above normal. In the Indo-Gangetic plains, the temperature has also been recorded 8 degree Celsius above normal.
How is high temperature responsible for dust storms?
- Higher temperatures mean less soil moisture, more dust and more desertification. This creates favorable conditions for the origin of the “Dust Bowl”, where wind speeds exceed 130 km/h resulting in the formation of more destructive storms.
Is this disaster natural, or man-made?
- It is essentially the result of a combination of factors that we humans are doing locally and globally, ranging from soil mismanagement and desertification to global emissions of carbon dioxide. These activities are continuously heating the surface of the earth, due to which such unique and unusual is happening.
Impact on environment and health:
Due to dust storms, the amount of fine particles in the air increases, which worsens the air quality. Wind blowing of soil, sand and rock particles, dust blown by vehicles, dust from excavation and construction work also play an important role in increasing the number of these fine particles. A worrying rise in PM10 levels was recorded due to dust storms blowing over western parts of India. The air quality index crossed 500 at many places in Delhi.
