At the moment, North India is going through early winter and it there is sharp drop in temperatures and cooler nights. This has led people including the citizen and scholars to develop questions touching on the causes and effects of this phenomenon. Below are the key reasons that are believed to have caused this phenomenon.
Climate Change and Global Warming
Climate change is cited to be one of the reasons for the early cold wave. People often define global warming as an increase in average temperatures but it contributes to extreme weather conditions such as this sudden cold. With the Arctic’s temperatures rising and the polar ice caps melting, the jet stream can be disturbed and bring frozen air right into areas that have normally anticipated relatively warm winters.
Atmospheric Conditions
Different weather factors have a causal attribute to the occurrence of cold wave. Earlier over the region, there may be high pressure systems, which mean that you find very few clouds and little or no wind which makes the temperatures to fall at night. Furthermore, absence of cloud leads to reduced insulation hence cooler night time.
Urbanization and Heat Islands
It has also become apparent that early cold wave is linked to urbanization. Continual growth of urban areas and constructions with concrete surfaces has developed a situation where structures ‘island’ themselves by emitting more heat than surrounding agriculture tracts. However, these heat islands can also contribute to higher amplitude of temperature fluctuations, that is, days are hot while nights are cold.
Forest conversion and Land cover changes
However, deforestation, changes in land use has moreover intensified the situation. Economic activities such as deforestation cut off the insulation of natural vegetation thus causes relatively lower temperatures in the region affected. Also, change in the use of land for agriculture by developing urban infrastructure can also change the climate variability patterns and result to early episodes of cold waves.
Effects on Agriculture and Livelihood
The early cold wave a is a major concern in agriculture and livelihood in the northern Indian region. Due to these conditions some crops which are deficit in unavoidable weather conditions like wheat and mustard, may easily get damaged which might lead to loss in yield. The same applies to the farmers as they struggle to protect their products (livestock) from the extreme cold, feed, and water.
Health Concerns
The nights are therefore cold and this goes with the poor health condition especially to the old, children and patients with other diseases. Cold climatic conditions are known to cause respiratory diseases, hypothermia and many other ailments. Measures that residents have to adopt range from putting on warm clothing and making sure their houses are warm enough etc.
Mitigation and Adaptation Strategies
The only way to deal with the early cold wave is by establishing measures of preventing and managing them. This involves such things as encouraging the proper use of land, afforestation, and the creation of future proof farming systems. Moreover, optimization of regulation of thermal environment to decrease heat islands or increase areas of green territories may be useful to address the problem of cold waves.
What are Cold wave or Severe Cold wave?
A cold wave is a climatological process including an abrupt and statistically substantial decrease of temperature during a particular time span. In its definition, IMD categorizes a cold wave as weather condition that results in the temperature settlement below 10 degrees Celsius over the plains of India and below zero degrees Celsius in the hilly areas. A severe cold wave is described as a situation whereby the temperatures drop even lower than the normal so that plains are at a temperature of 6.4°C or below 2°C. These conditions may lead to respiratory diseases, blood pressure complications and even diseases caused by lack of sunlight for instance bone and joint pains.
Why Cold Wave Has Started In North India Earlier This Year?
Generally, cold waves in North India are generally noticed during late-December, January. But this year cold wave conditions began earlier in the region, few days before the weather prediction of the meteorological department. Several factors have contributed to this early arrival:
- Absence of Cloud Cover: Clouds are very important structures in the trapping of heat and subsequent emission into the atmospheric space. This year there was not much of thick clouds hence more heat escaped from earth’s surface resulting to low temperatures.
- Himalayan Snowfall: Snowfall in the upper part of Himalayas triggers cold winds blowing in the region. This year, much has been deposited by snow since the onset of cold conditions has been witnessed early this year.
- Subsidence of Cold Air: Incoming cooler or dry air near the surface, called subsidence had been more distinct this year. This has an effect of causing temperatures to reduce in the region.
- La Niña Phenomenon: La Niña is usually marked by lower than average sea surface temperatures over the tropical Pacific Ocean. That is why it tends to strengthen and enhance the cold waves, or in other words, raise their frequency. The present La Niña has contributed to the early onset of cold waves in the Northern parts of India.
- Western Disturbances: These are extra tropical storms that develop in the Mediterranean region and bring occasional wintertime rain to North India. This year has seen the occurrence of western disturbances which has fade temperatures down because of the cold winds and precipitation coupling them.
This, the early occurance of cold waves, hastened the freezing effect on the area, with minimum temperature in some areas below the normal range. For instance, Delhi prevailed a lowest temperature of the season at 4.5°C, Adampur in Punjab also marked 1.8°C minimum temperature. People have shown adverse health effects owing to extreme cold, and they have also been unable to go about their normal activities.
Why are nights warmer than normal and days cooler in North India?
The drastic in climatic conditions of North India wherein nights are severely cold comparatively the days are still warm can be explainable on several grounds of atmospheric and climatic in nature.
- Radiative cooling: The main factors causing this are the fact that during the night there are no clouds in the sky. Instruments that are clear let the heat accumulated by earth bottom during the day to emit back to atmosphere more efficiently. Radiative cooling is the process that creates a sharp temperature difference during the night resulting to cold nights.
- Lack of Cloud Cover: They shield the heat and warm the surface during the night since they are like a blanket to the surface. This implies that the heat generated by the sun cannot be trapped by a layer of clouds hence the surface of the earth cools very fast. This is because high pressure systems which prevail in these areas during the winter produce clear, but cold nights.
- Dry Air Masses: In winter, in North India, there is also dry air which causes temperature to drop during night. It implies that moist air can retain more heat than dry air because it has a higher heat holding capacity. Since relative humidity is low, body loses heat quickly hence cold nights. Moreover, the continued winds from the northwest reduce the temperatures in the region through bringing cooler air in the evening.
- Diurnal Temperature Variation: The extent of the difference between the daytime temperature and the night-time temperature is generally referred to as diurnal temperature variation, and is particularly marked where the climate is dry, and there is little cloud cover. Warm temperature though during the day, the sun directly affects the surface of the earth expending heat energy faster than during night. At night, when there are no insulating factors such as cloud or moisture around, there is always cooling.
La Niña and its Impact on the Indian Subcontinent
La Niña is a climate phenomenon translating from Spanish as ‘The Little Girl’ and is defined by cooler than normal sea surface temperatures in the central and eastern Pacific Ocean in the equatorial region. It is the opposite of El Niño, during which have higher sea surface temperature in the same places. All these are associated with the El Niño-Southern Oscillation (ENSO) that extensively impacts world climate systems.
Mechanism of La Niña
La Niña is a situation, which sees powerful trade winds pushing warm maritime surface currents towards Asia leaving cold sea waters in America by pumping up water from the depths of the ocean. These changes in temperatures of the oceans cause variation to atmospheric circulation thus changing weather on the globe.
Impacts on Indian subcontinent
La Niña has several notable effects on the Indian subcontinent, particularly on the monsoon season and overall climate:
- Enhanced Monsoon: In a nutshell, La Niña enhances the intensity of the southwest monsoon in sub-continent and experiences above par rainfall. This is advantageous to agriculture more particularly to rain fed areas as it help recharge water and increase yield production.
- Increased Rainfall: The improved monsoon means more rainfall over the Indian peninsula and this means flooding in certain regions. Although this is very helpful for agriculture, this can lead to deterioration of structures and challenges during most activities.
- Cooler Temperatures: La Niña can reduce temperatures throughout the region, especially during winter because it registers cooler weather patterns. This is because of cold air masses and the westerlies that blows chilly air from the higher latitude.
- Impact on Agriculture: As mentioned, warmer temperatures increase rainy season yields, but cool temperatures mean the yields are unlikely to be sustained into the dry season. The extra water is healthy for the crops although the low temperatures are healthy for some crops while being unfriendly to others in as far as growth and produce yield is concerned.
- Health Implications: The cooler temperatures also bring health risks for those in the community especially the elderly and young children. Infected with flu or other diseases that affect the respiratory system can spread during this time or even other illnesses in general.
- Economic Impact: The impacts of La Niña on agriculture and infrastructure can partly be very costly. Even though, high rainfall volume compared to normal entails an improvement of agricultural output and food production, extreme rainfall and flooding harm harvest and decrease the food production, which in return impacts the income of farmers and the economy in large.