The elements which comprise the meteorological environment are: Atmospheric pressure, Air temperature, Humidity, Rainfall, Direction and speed of wind and Movement of clouds and character of weather.

1. METEOROLOGICAL
ENVIRONMENT
-Dr. SASI KUMAR PJ

2. Objectives
• To know about various Meteorological elements
• To know how are they measured
• To know what are their effects on health

3. Meteorology
The branch of science
concerned with the
processes and phenomena
of the atmosphere,
especially as a means of
forecasting the weather.

4. Meteorological environment
The elements which comprise the meteorological
environment are:
1. Atmospheric pressure,
2. Air temperature,
3. Humidity,
4. Rainfall,
5. Direction and speed of wind and
6. Movement of clouds and character of
weather.

5. Climate
Is a geographical
concept representing a
summation of the whole
range of meteorological
environment.

6. Atmospheric pressure
• Barometric pressure.
• It is the pressure within the atmosphere of Earth.
• Pressure at earths surface close to the sea level
averages 760 mm of Hg (“one atmosphere of
pressure”).
Pressure Altitude
Pressure Altitude

7. Barometers
1. Fortins Barometer 2. Kew Pattern Station Barometer
3. Barograph

8. Effects of atmospheric pressure on health
Air density
PaO2
Physiological effects :
1. Increase in respiration
2. Increase in conc. of Hb
3. Increase in cardiac output

9. AMS HAPE
1. Relatively common &
harmless.
2. Characterized by
headache, insomnia,
breathlessness, nausea,
vomiting and impaired
vision.
1. Generally appear on 3rd
day at high altitude.
2. Characterized by cough,
irregular breathing,
oligurea, mental confusion
and hallucinations,
Seizures and coma.

12. Depth
Pressure
For every 33 feet depth below see level, 1 atm. pressure incre

15. Narcotic action
Loss of mental
functions
Unconsciousness
Convulsions,
Death

17. Air temperature
1. Latitude
2. Altitude
3. Direction of wind
4. Proximity to sea

18. Measured by Thermometer
1. Boils at high temperature (356.7 °C)
2. Regular expansion
3. Level can be easily seen
Alcohol thermometer also used.

19. Essential conditions :
1. Air should have free access
to the bulbs of thermometer,
2. Thermometer should be
protected against radiant
heat.
Stevenson Screen
Used in all the meteorological observatories in India.

20. Types of thermometer
1. Dry bulb thermometer,
2. Wet bulb thermometer,
3. Maximum thermometer,
4. Minimum thermometer,
5. Six’s maximum and minimum thermometer,
6. Globe thermometer,
7. Wet globe thermometer,
8. Silvered thermometer,
9. Kata thermometer.

24. 4 cm
1.8 cm
• Alcohol thermometer,
• Cooling power of air.
Kata thermometer
—100°F
—95°F
1. The standard kata - 100-95°F
2. The high temperature kata - 130-125°F
3. The extra high temperature kata - 150-145°F

25. Heat stress
Heat stress is a condition where too much heat is
absorbed by a person or an animal and causes stress,
illness or even death.
Factors which influence heat stress :
1. Metabolic rate,
2. Air temperature,
3. Humidity,
4. Air movement &
5. Radiant temperature.

26. Heat stress indices
1. Equatorial Comfort Index - temperature of still and
saturated air.
2. Heat Stress Index - percentage of the heat storage capacity
of an average man.
0 - No thermal stress
10-30 - Moderate to mild heat strain
40-60 - Severe heat strain
70-90 - Very severe heat strain
100 - Upper limit of heat tolerance

27. 3. Predicted Four Hour Sweat Rate (P4SR)
• It is a rate at which man
sweats.
• Good index of heat stress.
• Only applicable in situation
where sweating occurs.
• 4.5 lit in 4 hours is the upper limit of tolerance and
2.5 lit in 4 hours is considered optimal for a
working man.

28. Effects of heat stress
Heat stroke
Heat hyperpyrexia
Heat exhaustion
Heat cramps
Heat syncope

29. Preventive measures
1. Replacement of water
2. Regulation of work
3. Clothing
4. Protective devices
5. Work environment

30. Effects of cold stress
• Injury due to cold may be general or
local.
• Characterised by numbness, loss of
sensation, muscular weakness, desire
for sleep, coma and death.
• Temperature below freezing causes
frostbite - the tissues freeze and ice
crystals from in between the cells.
• Frostbite is common in high altitudes.
• Intake of hot fluids promotes general
rewarming.

31. Humidity
• Humidity or moisture is always present in the atmosphere.
• The amount of moisture is depends on the temperature of
air.
• Humidity may be expressed as absolute humidity or
relative humidity.

32. Absolute humidity
• Absolute humidity is the measure of water vapour
(moisture) in the air, regardless of temperature. It is
expressed as grams of moisture per cubic meter of
air (g/m3).
• The maximum absolute humidity of warm air at
30°C/86°F is approximately 30g of water vapour -
30g/m3.

33. Relative humidity
• It is the most common way of describing
atmospheric moisture.
• It is a percentage of how much moisture is in air to
the how much it can hold.
RH =
Water vapour content
Water vapour capacity
—————————-

34. Dew point
• If the air is cooled, the excessive moisture
precipitates of the particular temperature.
• It is an important measurement used to predict the
formation of dew, frost, fog and even minimum
temperature.
• High dew point indicate high water vapour content
and low dew point indicate low water vapour
content.

35. Measurement
Dry and wet bulb hygrometer.
Sling psychrometer
Assmann psychrometer.

36. Precipitation
• Collective term used for
rain, snow, hail, dew and
frost i.e all forms of water
precipitated from the
atmosphere.
• Measured by rain gauges.

37. Air velocity
• Measured by anemometer.
• Wind velocities normally
recorded at a height of 10 m.
• Velocities are measured in
metres per second.
• Kata thermometer is used to record air velocities as low
as 10 feet per minute.

38. Wind direction
• Wind vane is placed at a
height of 10m. from the
ground level.

39. Clouds
• Are observed for their form, amount,
direction and height.
• Gives insight into sequence of weather.
• From the state of sky and evaluation of
clouds, weather is described as fine, fair,
unsettled, bad and thunderous.

40. THANK YOU