2. Contents
Introduction
Types of heat waves
Mechanism of heat waves
Effects on human beings
Case study on Karachi
Causes of Karachi heat-waves
Heat waves disasters in history
Impacts of heat waves
3. 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, that
the body can not tolerate.
As temperature rises people animals and plants suffer
from heat stress.
4. Apart from death more and more people also suffers
from sunstroke, severe dehydration, with vomiting and
high fever.
And cause disruption to community infrastructure like
power supply, public transport and services. Also known as
“Silent Disaster”.
The condition become more severe in May and June in
Pakistan.
Cont..
5. Categorization
Based on a physical meteorological perspective, heat-wave
events can be categorized into two broader types:
6. Dry heat-waves
Characterized by dry weather conditions with clear skies
and large inputs of solar radiation.
Accompanied by windy conditions, which can increase heat
stress.
Dry heat waves usually occur in locations with a
continental or Mediterranean climate or where air is
warmed adiabatically.
7. Moist heat-waves
Characterized by very warm, oppressive, humid
conditions throughout the day and night.
Often with nocturnal cloud cover, a feature that
prevents loss of heat accumulated throughout the day
and thus provides little night-time relief.
Such heat wave often a feature of mid-latitude
temperate and maritime climates and may be endemic to
some regions.
8. Mechanism
A heat wave is caused by a system of higher
atmospheric pressure.
In a high pressure system, air from upper levels of the
atmosphere descends and rotates outward.
As it comes down, it becomes compressed, which
increases temperature and dries it out.
9. Effect on human beings
o Heat stroke
o Dehydration
o Sun burn
o Air pollution
o Drowning
10. Karachi 2015 heat wave
During summer season, Karachi has displayed very
high occasional day temperatures up to 44.8°C .
With the heat index ranging between 58.3°C -66.1°C
This severe heat wave event persisted for
consecutive 5-days from 19-23 June.
Over 2500 innocent souls have lost their valuable
lives to the sweltering heat.
11.
12. Causes of Karachi heat wave
Following are the causes of heat-wave event in Karachi.
14. Some miserable heat-wave
disasters in history
Europe, 2003:
About 71,310 people died
Russia, 2010:
About 55,736 people died
Europe, 2006:
About 3,418 people died
India, 1998:
About 2,541 people died
Pakistan, 2015:
About 2500 people died
21. Cont..
o Increased energy demand, e.g. greater demand for air
conditioning.
o Shifts in tourism preferences due to higher
temperatures.
o Human morbidity and mortality, particularly among the
elderly & infirm.