Local Winds of India

Winds are atmospheric phenomenon attributable to difference in temperature and atmospheric pressure. They are significant component in establishing and regulating the weather and climate of a particular place as well as of global atmospheric phenomenon. Winds operate in different climatic scale in terms of its spatial and temporal aspects. They operate at planetary scale known as planetary winds; seasonal scale known as seasonal or periodic winds and regional scale known as local winds.

Local winds are winds with limited spatial and temporal scale as they effect a limited area and operates over a shorter period of time. There are many ways in which local winds effect the weather and climate of a particular places. Many local winds blow over different regions of India. The influence of these local winds ins not only limited to the climate and weather but also shapes the economic, cultural and social characteristics of the region. 

Local winds of India –

Aandhi, also known as Kali Aandhi are dust storms affecting the north western and central part of India. These storms are formed due to development of strong pressure gradient in the region late spring before monsoon season. Due to high surface heating in the dry Arabian Peninsula and the Thar desert, the loose soil/sand particles are transported through westerly winds to northern- central India (Middleton, 1986). These dust storms may become ferocious and cause destruction to life and property. The level of pollution in many urban centres like Delhi rises and the amount of suspended particles increase in air.

 

MODIS TERRA satellite image showing thick dust storms over India and Pakistan on June 9, 2003. Image courtesy - NASA

Loo are hot, dry winds blowing throughout the daytime in north and western India during the month of May and June. Loo winds are developed due to formation of the Monsoon Low Pressure Trough in northern India. To maintain balance, the hot dry winds of the surrounding areas move in causing formation of Loo. These dry winds are responsible for loss of life due to dehydration. However, it has some positive influences as it facilitates the process of separating the chaff from the grain. There is also decline in number of insect borne disease like malaria due to decrease in mosquito population.

Kalbaisakhi winds hitting Kolkata on 24 May, 2010. Photo Courtesy - Biswarup Ganguly, Wikipedia

 

Kalbaisakhi are the local winds affecting the eastern Indian states of West Bengal, Assam, Bangladesh and parts of Odisha and Bihar. It is known as different names in different states. Kal- Baisakhi means 'a fateful thing' in the month of Baisakh (Roy and Chatterji, 1929). In Assam, these are called Tea showers and Bordolichilla, and in Odisha as Bordoisila or Bardoli Chhera. These pre-monsoonal winds originate in the Chhota Nagpur plateau and blows eastwards under the influence of Westerlies. These warm winds when come in contact with moisture laden air and moves over elevated Himalayas in Assam and North Bengal, results in sudden rise in wind speed, lightning, thunder and hail and sometimes destructive tornadoes. It can cause destruction by uprooting trees and small houses. But then again, they sustain the pre-kharif crops like jute and paddy, and a large number of vegetables and fruits till summer season.

Mango showers are rains bearing local winds known with many different names as April rains, summer showers, coffee showers and cherry blossom showers. Names with cultivation prefix has been given to these light rains as it is beneficial for their growth. These pre-monsoonal winds are mainly experienced in south India prevailing along the coast of Kerala, Karnataka and parts of Tamil Nadu. They originate in the Bay of Bengal as the result of thunderstorm development.

Elephanta is a post monsoonal local wind impacting the Malabar coast of India. These are south easterly moisture laden winds which announces the beginning of dry season after monsoons and end of the rainy season. 

If you are more interested in winds; Earth, Windy, Windfinder are web based utilities which visualizes winds with wind direction, speed and other weather variables.

References - 

Middleton, N.J. (1986), A geography of dust storms in South‐West Asia. J. Climatol., 6: 183-196. doi:10.1002/joc.3370060207

Roy, S., Chatterji, G. Origin of Nor'westers. Nature 124, 481 (1929). https://doi.org/10.1038/124481a0

River of ice

Lambert - Fisher Glacier, Antarctica. Image from Google earth

 

 

Glacier is a moving mass of ice. It is different to iceberg in that, it moves over land and is much larger in size. The term “glacier” is from the French word ‘glace’, which has been taken from latin word ‘glacies’, both meaning ice.

Glaciers are formed due to snow fall and accumulation of ice over longer periods of time. With increasing snowfall, ice accumulates in glaciers. This leads to two different processes in a glacier formation. First is the process of compression within the glacier. It makes the glacier much denser and heavier. Secondly, increased weight of the glacier makes it move downwards, towards a lower area.

While moving down, glaciers erode and deposit, thus creating many features. Antarctica, Greenland, Alaska, Himalayas are some of the regions with glaciated landscapes.

Why are glaciers relevant?

Though, the relevance of a glacier may be mainly as a vacation spot for people not living in its vicinity. Glaciers are much more than that. It is relevant to human life economically, environmentally as well as socially.

It is very difficult to assess the tangible economic value of a glacier for a nation or state. But it a priceless resource with immense direct and indirect values. Its importance can be analysed from a 2014 report by U.S. Geological Survey economists Catherine Cullinane Thomas and Christopher Huber and National Park Service economist Lynne Koontz. The report is about the economic gains from Glacier national park in 2014. The report shows the one year benefits received from the glacier park to the economy, in form of income and the employment generated in the area. This study is not only the single example of the economic relevance of a glacier. In reality, there are immense benefits and gains which are still not explored.

Environmentally, glaciers provide nutrients to soils, rivers, lakes and oceans. They are a great source of fresh water and has an important role in maintaining the water balance in climate. They are also important in maintaining the salinity level of the oceans. Infact, if we realise, glaciers are a relevant part of the whole environmental balance of nature. A minor change in this natural equilibrium may disrupt the whole system.

Khumbu Glacier- Highest glacier in the world. Image from Google Earth

 

Glaciers are relevant socially as well as culturally. They are sites of powerful sacred and symbolic meanings for local communities (Allison 2015). A study by Allison (2015) shows the spiritual connection of the communities in the Peruvian Andes, the Nepalese Himalaya, and the Meili Snow Mountains of Yunnan, China to the glaciers. Glaciers are source of many important rivers which are considered sacred by its masses.

Some Facts about Glaciers -

Largest glacier in the world - Lambert-Fisher Glacier in Antarctica, 400 km long, and up to 100 km wide.

Highest glacier in the world - The Khumbu glacier in north-eastern Nepal. Its elevation is 4,900 m at its terminus to 7,600 m at its source.

Oldest glacier – The oldest glaciers ice can be found in Antarctica which is about 1,000,000 years old. In Greenland it is more than 100,000 years old.

References –

Allison, Elizabeth. (2015). The spiritual significance of glaciers in an age of climate change. Wiley Interdisciplinary Reviews: Climate Change. 6. 10.1002/wcc.354.