The document discusses various meteorological elements, their measurement, and their effects on health, focusing on atmospheric pressure, air temperature, humidity, and precipitation. It highlights the physiological impacts of high and low altitudes, the significance of humidity levels on human comfort, and the relationship between temperature and humidity regarding heat stress. Additionally, it covers measurement techniques for different meteorological parameters and the implications of weather conditions on health and safety.

1. Meteorological Environment
Dr Rupesh Sahu, M.D.
Assistant Professor
Department of Community Medicine
BMC, Sagar

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
• Following Elements comprise
Meteorological Environment
1. Atmospheric pressure
2. Air Temperature
3. Humidity
4. Rainfall
5. Direction & speed of wind
6. Movement of clouds & character of weather

5. ‘Climate’
• A geographical concept representing a
summation of the whole range of
meteorological environment

6. Measurement
• By Barometer.
• 3 types
– Fortins b
– Kew pattern station b: used in Indian Meteorological
dept
– Barograph

7. Kew Pattern Station Barometer

8. Effect of exposure to High Altitude
(Low Pressure)
• Human is physiologically adapted to live at
One atm pressure.
• Air is less dense- partial pressure of O2 is
also less.
• Physiological Effects
– Increase in respiration
– Increase in concentration of Hb
– Increase in Cardiac output.

9. Effect of sudden exposure to High
Altitudes
Acute Mountain sickness
• Relatively common,
harmless, transient
condition
• c/b
– Headache
– Insomnia
– Breathlessness
– N,V
– Impaired vision
High altitude pulmonary
oedema
• Appear on about 3rd day
of high altitude.
• As PE develops there
also develops
– Cough
– Irregular breathing (cheyne
stokes breathing)
– Oligouria
– Mental confusion
– Hallucination, stupor, coma

10. Effect of exposure to Low Altitude
(High Pressure)
Increased Depth
Gases in blood (O2, N2,
CO2) dissolve increasingly
N2: Narcotic action
CO2: increase narcotic action of N2
O2: Convulsions, death.
Person Comes up: gases released (undissolved)—Air
embolism

11. 2. Air Temperature
• Represents Degree of hot/coldness of air.
• Influenced by
– Latitude of place
– Altitude
– Direction of wind
– Proximity to sea

12. Air Temperature
• Measurement : Thermometer
• Commonly used are Mercury thermometers
– Boils at high temperature (356.73 degree celcius)
– Has regular expansion
– Levels can be seen easily.
• Alcohol thermometer used at many places
since it has advantage of not solidifying even
at lowest known temperatures.(*freezing
point of mercury: -38.83 degree celcius)

13. Air Temperature
• Essential conditions for use of
thermometers:
– Air should have free access to the bulb
– Should be protected against radiant heat.
Stevenson screen
Used in all meteorological observatories in India

14. Stevenson’s Screen

15. Types of Thermometers
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

16. Dry & Wet bulb thermometer

17. Six’s Maximum and Minimum
thermometer

18. Max min thermometer

19. Globe Thermometer

20. Globe Thermometer

22. Wet bulb globe thermometer

23. Wet Bulb Globe Temperature
• It is used by industrial hygienists, athletes, and
the military to determine appropriate exposure
levels to high temperatures.
• In hot areas, some US military installations display a
flag to indicate the heat category based on the
WBGT.
• The military publishes guidelines for water intake
and physical activity level for acclimated and
unacclimated individuals in different uniforms based
on the heat category.

24. Heat stress indices
• Include
– Equatorial comfort index
– Heat stress index
– Predicted four hour sweat rate

25. Effects of Heat stress
1. Heat stroke
2. Heat hyperpyrexia
3. Heat exhaustion
4. Heat cramps
5. Heat syncope

26. Preventive measures
– Replacement of water
– Regulation of work
– Clothing
– Protective devices
– Work environment

27. Effects of Cold stress
• Hypothermia :
– c/b numbness, loss of sensation, muscular
weakness, desire for sleep, coma and death.
• Immersion/ trench foot
• Frostbite

28. 3. Humidity
• Moisture
• Amount of moisture which air can hold
depends upon its temperature.
• Humans are very sensitive to humidity, as
the skin relies on the air to get rid of
moisture.
• Expressed as
– Absolute humidity
– Relative humidity

29. Absolute humidity
• Weight of water vapor in a unit volume of
air
• Expressed as gms per cubic meter of air

30. Relative humidity
• Most common way of describing atmospheric
moisture.
• Relative humidity is the ratio of the amount of
water vapour actually in the air to the
maximum amount of water vapour for
saturation at that particular temp & pressure.
• A reading of 100 percent relative humidity
means that the air is totally saturated with
water vapor and cannot hold any more,
creating the possibility of rain.

31. Relative humidity
• The process of sweating is our body's attempt to keep
cool and maintain its current temperature.
• If the air is at 100-percent relative humidity, sweat will
not evaporate into the air. As a result, we feel much
hotter than the actual temperature when the relative
humidity is high.
• If the relative humidity is low, we can feel much cooler
than the actual temperature because our sweat
evaporates easily, cooling us off.
• Very low RH causes skin cracks, dry flakes, itch, irritates
mucous membrane in nose, throat (itchy throat).
• Dry nasal passages permit bacteria to incubate causing
persistent infection.

33. Dew point
• Represents TEMPERATURE to which air
would have to be cooled (with no change
in pressure/moisture) for saturation to
occur.
• High Dew point indicates high water
vapour content and low dew point indicate
low water vapour content.
• Frost point

34. Measurement of Humidity
• Dry & wet bulb Hygrometer
• Sling Psychrometer
• Assmann Psychrometer

35. Dry & wet bulb Hygrometer

36. Relative Humidity chart

37. Sling Psychrometer
4 revolutions per second=15 m/s air speed

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

39. Rain guage
*Rim should be exactly horizontal
*one foot above the ground level

40. 5. Air velocity
• Measured by Anemometer & Kata thermo.
• Measured in meter/s : described as
– 0.5 m/s: complete calm, smoke rising vertically
– 3.3 m/s: slight breeze, leaves rustling
– 10 m/s: Strong wind, larger branches of trees
moving
– 15-20 m/s: Storm
– 25-30 m/s: Gale
– 30-50 m/s: Hurricane

41. Anemometer

42. Wind direction

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