This document discusses key elements of meteorology and the meteorological environment. It describes atmospheric pressure, air temperature, humidity, rainfall, wind speed and direction, and cloud movement/weather. It covers instruments used to measure these elements like barometers, thermometers, hygrometers, and rain gauges. It also discusses effects of exposure to high and low altitudes/pressures on humans.

1. Meteorological Environment

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

3. 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

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

5. Measurement
• Instrument used to measure atmospheric
pressure are called Barometer.
• 3 types
– Fortins Barometer
– 'Kew pattern' Station Barometer : used in Indian
Meteorological
dept
– Barograph- continuous record of atmospheric
pressure

6. Kew Pattern Station
Barometer
Barograph

7. 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.
• Cant survive above 25000 F
• Physiological Effects
– Increase in respiration
– Increase in concentration of Hb
– Increase in Cardiac output.

8. 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
odema
• Rare below 12000 F
• 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

9. 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
•Pressure increase 1
atm / 33 F
•Max 10 ATM reached

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

11. 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)

12. 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

13. Stevenson’s Screen

14. 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

15. Dry & Wet bulb thermometer
•Ordinary thermometer
•Mounted in stevenson’s screen
at a height of 1.20- 1.80m above
ground level
•The wick is covered by wet
muslin cloth
•Shows lower temp as dry bulb
•If both show same temp that
means the air is saturated with
moisture (rare)

16. Six’s Maximum and Minimum
thermometer

18. Globe Thermometer
Measure mean radiant
temperature.

19. Globe Thermometer

20. 4cm length
and cm dia.
Reading from
95- 100 F

21. Wet bulb globe thermometer

22. 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.

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

24. Effects of Heat stress
1. Heat stroke- 110F
2. Heat hyperpyrexia-106F
3. Heat exhaustion- 102F
4. Heat cramps
5. Heat syncope

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

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

27. 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

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

29. 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.

30. 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.

32. Dew point
• The temperature at which water vapour in
the air becomes saturatedand
water droplets begin to form (condensation
begins)

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

34. Dry & wet bulb Hygrometer

35. Relative Humidity chart

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

37. 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
•Wind vane
•Above 10 m
height
•4 main and 8/ 16
sub categories

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.