This document discusses heat waves and cold waves. It provides definitions of heat waves and criteria used by the Indian Meteorological Department to declare heat waves. It notes that heat waves have impacted 15 Indian states so far in 2022, with Rajasthan and Madhya Pradesh most affected. Cold waves are defined as a rapid drop in temperature over 24 hours. The document discusses impacts of heat waves and cold waves on human health, agriculture, animals, and infrastructure. It provides tips on prevention and mitigation measures during heat waves and cold waves.

1. PGS - 506
TOPIC:- HEAT AND COLD WAVES
Dr. Rahul
Dangi
DR. RAHUL DANGI
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2. HEAT WAVES INTRODUCTION
 It is a prolonged period of excessive heat often accompanied by excessive
humidity.
 Heat waves occurs when there are a number of consecutive days with above
average temperature , than the body can not tolerate .
 The unusual and uncomfortable hot whether can impact on the human and
animal health and cause disruption to community infrastructure such as
power supply, public transport and other services.
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3. WORKERS IN INDIA TRAVEL KILOMETERES
IN HOT WAVES
Pictures – woman with small baby less than a year carry
luggage and baby too in hot waves
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4.  The Indian Meteorological Department (IMD) has given the following criteria for
Heat Waves: Heat Waves need not be considered till the maximum temperature of a
station reaches at least 40°C for Plains and at least 30°C for Hilly regions. When
the normal maximum temperature of a station is less than or equal to 40°C
 The weather agency declares a heat wave when a place registers a temperature that is
4.5 to 6.4oC more than the normal temperature for the region on that day. If the
temperature is over 6.4oC more than the normal, the IMD declares a ‘severe’ heat
wave.
 The IMD also uses another criteria to declare a heat wave which is based on absolute
recorded temperatures. If the temperature crosses the 45oC mark , the Department
declares a heat wave ; when it crosses 47, a ‘severe’ heat wave is declared.
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5. HEAT WAVES IN INDIA
 How bad has this year’s heat wave been in India?
 The early heat waves of 2022 that began on March 11 have impacted 15 Indian states
and Union territories (as of April 24), according to data from the India Meteorological
Department (IMD) that was analysed by Down To Earth.
 Rajasthan and Madhya Pradesh have suffered the most among the states, with 25 heat
wave and severe heat wave days each during this period.
 Surprisingly, after Rajasthan and Madhya Pradesh, the mountainous state of Himachal
Pradesh has been the most affected by heat waves this year with 21 heat wave and
severe heat wave days.
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6. WHAT GLOBAL EVIDENCE DO WE HAVE OF HEAT WAVES
HAPPENING ACROSS THE WORLD?
 The IPCC report says that every additional 0.5oC of warming will
increase hot weather extremes, along with extreme precipitation and
drought.
 Heat waves in India are likely to “last 25 times longer by 2036-2065” if
carbon emissions remain high and push global temperature rise to 4oC by
the end of the century, according to an international climate report
published October 28, 2021, covering the G20 countries.
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7. WHAT IS ‘WET-BULB’ AND WHY DOES IT MATTER ?
 Wet-bulb temperature is a measure of humidity in the air. Factoring in humidity along
with the heat, called the heat index, helps us determine what the temperature actually
‘feels like’.
 Humidity combined with heat is deadlier for human health and wellbeing.
 Humans with their sweat-based cooling system, have been well-designed to beat the
heat. But there is a limit to the level of heat and humidity we can cope with. A wet-
bulb temperature of 35°C is considered the maximum limit of humidity that humans
can handle. Beyond this, the body can no longer effectively cool itself via
perspiration.
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8. WHAT HAVE BEEN THE IMPACTS OF HEAT WAVES?
 The unlikely impact of the current heat
waves would occur in the Himalayan
regions of Himachal Pradesh, Jammu and
Uttarakhand that are not used to heat
waves and not well adapted to the extreme
temperatures.
 One major impact in these regions would
be on the accelerated melting of glaciers
due to extreme temperatures which are the
main source of water for the people living
there.
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9. WHAT IS BEING DONE GLOBALLY, AND WHAT ELSE NEEDS TO
BE DONE?
 The first Heat Action Plan (HAP) was developed for Ahmedabad in 2013. Under this, people
will receive weather alerts through SMS on mobile phones and medical professionals will be
trained to increase preparedness. The initiative avoided 1,190 deaths a year, according to a
study published in 2018, that evaluated the plan’s impact on death rates.
 The third instalment of the IPCC’s Sixth Assessment Report (AR 6) focuses on the
importance of urban green and blue infrastructure such as green walls, greenways, street trees,
urban forests, green roofs, blue spaces, to cool urban areas. Urban trees can mitigate some of
the impacts of climate change by reducing the urban heat island effect and heat stress. In
addition, they can reduce stormwater runoff, improving air quality, and supporting health and
well-being in areas where the majority of the world’s population resides.
 Asphalt and concrete store heat longer and gradually releases heat at night , which produces
significantly higher night temperatures in urban areas known as urban island effect .
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10. HEAT WAVES KILL AND INJURE
 Heat wave is one of the major disaster for many countries , develops
slowly and kills and injures many animals and people more than any
other disaster.
 Hence called as silent disaster.
 In India the condition becomes more severe in may and June.
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11. Heat waves caused unfold mystery to people all
over the world.
 In 1998 , about 1500 people were died in China
and in 1997 about 2000 people fell into heat
wave in Greece.
 Similarly in India the heat wave took 302 lives in
the year 1998 and more than 2000 people in
2002. in 0rissa, heat wave caused 2042 deaths in
1998 and more than 1200 deaths in 2002 in
Sothern India.
 Data collected by IMD reveals that the average
annual loss of human life due to heat wave over
the India is 153.
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12. SIGNS AND SYMPTOMS OF HEAT RELATED ILLNESS
 Sunburn
 Pale skin
 Heat cramps
 Heat exhaustion
 Heat stroke
 Weakness
 Fainting/collapse
 Nausea
 Headache
 Dizziness
 Rapid pulse
 Drowsiness
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13. EFFECT ON HUMAN BEINGS
 In many parts of world, every summer, thousands of people suffer from heat stress
where their bodies absorb more heat than they expel.
 Depletion of salt and electrolyte in the body may cause heat cramps.
 Hard work under direct sun may lead to heat exhaustion. Usually, it is the cumulative
effect of hot days without the relief of cool nights and exposure to exhaustion.
 sunburn can retard the body`s ability to shed heat, and may increases the severity of
the heat disorder.
 In severe heat there is dehydration and body may overheat, leading to hyperthermia.
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14. WHO IS AT MOST RISK
Elderly and children Outdoor workers, military and farmers
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15. EFFECTS ON ANIMALS
 Domestic animals and poultry birds are
particularly vulnerable to heat waves
 When their is no enough shed or water
for animals, they may change their
behaviour.
 Animal will look for shelter from the
heat under trees or near bushes, start
painting , drooping , drink more water
and have reduced appetite for food .
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16. AGRICULTURE AND CROP
 The wheat crop in the rabi season in
Punjab, Haryana and Uttar Pradesh has
been impacted by heat waves. Many
farmers have reported losses between
20 and 60 percent in these states.
 This happened because the heat waves
were early this year and the
temperatures affected the wheat plants
during their growth stage, leading to
shriveled grains which fetch lower prices
in the market, resulting in losses.
 To reduce agricultural losses due to heat
waves, heat-tolerant varieties of wheat
need to be developed.
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17. INFRASTRUCTURE
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18. PREVENTION DURING HEAT WAVE
 Heat waves can be serious but it is one
of the disasters, which can be managed.
• Control the temp. at home
• In the street avoid direct sunlight
• Keep rooms cool by using shade cloth
or reflective material on the outside of
the window
• Limit physical activity at the hottest
times of the day
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19. WATER
 During hot summer water consumption
increases drastically and often causing
shortage of drinking water.
 Lack of water in most of wells , ponds,
tubewells, and other water bodies during
hot summer seasons, which has an
adverse effect on human being and
animal population.
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20.  Drink a lot of water
 Listen to local weather forecast so that we can
know if a heat waves on the way
 Avoid heavy protein food like meat, dairy
products etc. which raise body heat and increase
fluid loss
 If u must go out then wear light weight, light
coloured, porous clothes
 Do not leave children or pets in a parked
vehicles.
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21. COLD WAVES
 An unusually large and rapid
drop in temperature over a short
period of time (24 hours) . It’s a
weather phenomenon that is
distinguished by a cooling of the
air.
 A rapid and considerable drop in
temperature, usually affecting a
large area .
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22. WHAT IS COLD WAVE ?
 The IMD records a cold wave when the minimum temperature is equal to or
less than 10 degree Celsius at a weather station in the plains, and is 4.5
degrees to 6.4 degrees below the normal temperature for that period.
 A cold wave may also be recorded at a station in the plains when the
minimum temperature is less than or equal to 4 degree Celsius.
 For hilly regions, a cold wave is declared when the minimum temperature is
less than or equal to 0 degree Celsius and the minimum temperature is 4.5
degrees to 6.4 degrees below the normal
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23. WHAT DAMAGE CAN ARISE ?
 Cold wave also could cause health problems such as fever , heart
disease, asthma, mayocardial infarction, angina pectoris and
others.
 Fatal road accident can occur due to foggy weather.
 The homeless, people who must spend time outdoors (e.g. for
works ) and the elderly are particularly vulnerable to the effects of
cold waves.
 Difficult for animals including human to live and may be unable to
reach needed food and die due to hypothermia or starvation.
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24. CHARACTERISTICS
 The characteristics of cold wave vary in different
geographical environment. Sometimes it produces
gale with less snowfall especially sandstorm and
low temperature . cold wave always brings wind and
heavy snow. In different area , cold waves comes
with rainfall .
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25. COLD WAVES IN INDIA
 India recorded 99 days of cold waves in 2020, according to IMD. There has been
a nearly 2.7 times increase in the number of cold wave days from 2017-2020, the
report showed. Cold waves killed more Indians than heat waves from 1980-2018.
The number of cold wave days have been consistently on the rise since 2017.
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26. PREVENTIVE MEASURES
 When temperature drops quickly, people should add clothes especially keeping
hands and face warm.
 Close doors and windows .
 Mind slippery road when going out.
 Older peoples, babies, the weak patients should stay indoors.
 Have proper rest and do not over fatigued.
 Household that use coal stove should pay attention to gas poisoning.
 Use worm clothes, shocks and hand gloves.
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27. THANK YOU
DR. RAHUL DANGI
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