Wet bulb temperatures and heat action plans (HAPs) are extreme words, which are applicable in extreme situations. It is the kind of situation that Delhi and large parts of North India as well as coastal areas currently find themselves in, despite some cooling showers on the evening of May 4.
With several Indian cities in the grip of a severe heat wave with the temperature breaching the 45-degree mark, the average nationwide temperature in March was 33.1°C, beating the 32.7°C recorded in March 2021, which was the third warmest on record.
ALSO READ: With unprecedented, blistering heat in 2022, India's HAPs will be on severe test
So, what exactly is wet bulb temperature and the government’s highly ambitious Heat Action Plan? With such heat, a power crisis can never be far away. At this time of the extreme heatwave, India is witnessing an electricity shortage at its peak compared to the past six years. Moneycontrol talked to three leading experts to find out more about the new terminologies as the heat wave rises to new and scary levels.
KJ Ramesh, former director general of IMD
"Wet bulb temperature is the lowest temperature to which air can be cooled"
What exactly is wet bulb temperature?
Wet bulb temperature is the lowest temperature to which air can be cooled by the evaporation of water into the air at a constant pressure. It is therefore measured by wrapping a wet wick around the bulb of a thermometer and the measured temperature corresponds to the wet bulb temperature. The dry bulb temperature is the ambient temperature.
What is the difference between the two temperatures?
The difference between these two temperatures is a measure of the humidity of the air. The higher the difference in these temperatures, the lower is the humidity.
Is it available around the country?
Yes, it is. The India Meteorological Department (IMD), an agency of the Ministry of Earth Sciences of the Government of India, is one of the biggest weather forecasters in the world with one branch in every state. In addition, the IMD has six regional meteorological centres, each under a deputy director general. These are in Chennai, Guwahati, Kolkata, Mumbai, Nagpur and New Delhi. There is also a meteorological centre in each state capital. Other IMD units such as forecasting offices, agrometeorological advisory service centres, automatic weather stations (AWS), hydro-meteorological offices, flood meteorological offices, area cyclone warning centres, and cyclone warning centres are usually co-located with various observatories or meteorological centres. Climate scientists, however, say that its usage is more widely prevalent in the coastal areas where humidity remains a constant concern.
Priya Dutt, the Indian Institute of Public Health (IIPH), Gandhinagar, extensive researcher on wet bulb temperature
"Wet bulb temperature is like an index or a censor"
How would you describe wet bulb temperature?
Wet bulb temperature is an index, or a censor, a formula which helps us calculate the temperature, or more specifically the exact extent of humidity. It is used mostly in coastal areas.
What is the difference between normal and wet bulb temperature?
Measured on a different scale, compared to normal temperature, where 35 degree is the maximum threshold, wet bulb temperature of 32 degrees could imply that normal, fit persons will find the going tough and difficult to work.
With heat rising the way it is, the more crucial question is whether India is prepared for climate change? On the face of it, it may not appear to be so. Buildings with large glass panes are the order of the day and with a minimum 5 feet difference between buildings are hardly conducive to promoting greenery.
Dileep Mavalankar, head of Indian Institute of Public Health, Gujarat
“India has to take its Heat Action Plan more seriously"
What is the Heat Action Plan?
This plan includes early warning systems, colour coded temperature alerts, community outreach programme, capacity building networks among government and health professionals for preparedness and reducing exposure and staggered or reduced timings for schools and factories.
The central government, its agencies, and other stakeholders are working with 23 heat wave-prone states over 130 districts to develop heat action plans. The challenges they face are formidable, nothing more debilitating than the two-year-long pandemic, which has disrupted a system, which was coming into place.
The IMD Safar, for instance, has key information on its apps, but given the country's huge diversity, mere apps would not suffice. It needs full page advertisements on the lines of political publicity on rapidly rising temperatures.
How did HAPs come into being?
The basis of HAPs was the heat wave in Gujarat in 2010, which claimed, officially, 100 neonatal deaths in a single hospital in Ahmedabad alone. It prompted scientists from the National Research Development Corporation (NRDC), the Indian Institute of Public Health, Gandhinagar, the IMD and officials from the Amdavad Municipal Corporation to develop India’s first heat action plan specifically tailored for a city in 2013.
How does the system work?
The nodal officer at Ahmedabad sends out alerts: orange (very hot) if it is more than 40°C, red (extremely hot) for more than 45°C. Messages are then sent to the public through various media, to take precautions and not go out and hospitals are made ready to receive heat stroke cases.
India’s power crisis
The heat wave and coal shortage have led to a fall in electricity supply, particularly power generated through coal. A prolonged dry spell associated with severe heat waves has led to power crises in many states across the country, the worst hit among them being Punjab, Haryana, Jammu Kashmir, Rajasthan, Uttar Pradesh, Bihar, Jharkhand, Madhya Pradesh, and Maharashtra.
On April 29, for instance, the peak power demand for the country was 207.111 gigawatts (GW). The earlier record was broken recently with peak demand of 201.066 GW. However, the silver lining is that pre-monsoon activity is evident in parts of Northwest and East India since the beginning of May.
The Central Government has various projects like the Deen Dayal Upadhyaya Gram Jyoti Yojana (DDUGJY), the Integrated Power Development Scheme (IPDS), and Revamped Distribution Sector Scheme (RDSS) simultaneously running for achieving uninterrupted power supply for all the consumers.
The RDSS scheme is used to reduce losses on distribution utilities, which has an outlay of Rs 30,785 crore with an estimated gross budgetary support of Rs 97,631 crore from the Central government. There are also several steps taken by the Government in increasing power generation across the country.
These include thermal projects, large hydro projects that scale above 25 MW, nuclear capacity amounting to 8700 MW and 7000 MW of nuclear power projects. The government's focus on hydro, nuclear, solar, PV, wind and biomass is undeniable. Yet, the blistering heat has taken a toll on the best laid down government plans.
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