Meteorology: The word meteorology is from the Ancient Greek and meaning "the study of things high in the air." Luke Howard has been called “the father of meteorology” because of his comprehensive recordings of weather in the London area from 1801 to 1841 and his writings, which transformed the science of meteorology. Meatrology and its types by Muhammad Arslan Yasin, Sukhera Illustratorz

1. Community Medicine
Topic:
Meteorology and Its Elements
Submitted By:
Muhammad Arslan Yasin
Subject:
Community Medicine
SUKHERA ILLUSTRATORZ

2. Meteorology and Its Elements
Definition:
 The branch of science concerned with the processes and phenomena of the atmosphere,
especially as a means of forecasting the weather.
 Meteorology is the science that deals with the study of changes or phenomena occurring in
the atmosphere.
 Commonly known as 'weather,' meteorology focuses on the atmospheric variables related
to current or near-future conditions. Several weather elements describe the atmosphere
such as temperature, humidity, precipitation amount and type, wind direction and strength,
atmospheric pressure, and cloud cover.
Elements of Meteorology:
The elements of meteorological environment are:
1. Atmospheric pressure
2. Air temperature
3. Humidity
4. Air movement (Air velocity, Direction and speed of the wind)
5. Rain fall.
6. Precipitation
7. Visibility
8. Cloudiness (cloud type and cover)
9. Sunshine duration
Meteorology:
The word meteorology is from the Ancient Greek and
meaning "the study of things high in the air."
Luke Howard has been called “the father of meteorology” because of his comprehensive
recordings of weather in the London area from 1801 to 1841 and his writings, which
transformed the science of meteorology.
1.Atmospheric pressure:
Atmospheric pressure, also known as barometric pressure (after the barometer), is the
pressure within the atmosphere of Earth (the pressure exerted by the weight of the
atmosphere).
The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa.
101,325 Pa=760 mm Hg
The atmospheric pressure falls as the altitude increases as in high mountains and rises as
altitude decreases as in deep mines.
Atmospheric pressure ∝
Altitude
1
i.e. When aperson descends 33 feet (as in mines), he is exposed to an atmospheric
pressure of 2 atmospheres, i.e. 760 × 2 = 1520 mm Hg.
Measurement of atmospheric pressure:
The instrument used to measure atmospheric pressure is called ‘Barometer.
- ‘Kew Pattern’ station barometer is widely Used.
- Others are Fortin’s barometer, Aneroid barometer and Barograph.
Effects of Atmospheric Pressure:
The influence of atmospheric pressure on health is considered under two headings:
I. Effects of diminished atmospheric pressure.
II. Effects of increased atmospheric pressure.
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I.Effects of Diminished Atmospheric Pressure:
This occurs in high altitudes. Sudden exposure to high altitude above 10,000 feet, results
in ‘Acute mountain sickness’ (or aviator sickness) due to rarity of atmosphere and deficiency in
oxygen.
- This is characterized by headache, mental fatigue, irritability, irrational behavior, loss of
muscular coordination, insomnia, nausea, vomiting, breathlessness, and in severe cases there
may be bleeding from the nose, ringing in the ears, palpitation and even collapse.Later as
the pulmonary edema develops, the respiration becomes deep andirregular
(Cheyne-Stokes breathing) the person also develops oliguria, mental confusion,
hallucinations, later develops stupor, convulsions, coma and death supervenes.
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3. Acclimatization:
Human body has a remarkable power of adjusting itself to low oxygen pressure provided
the change is made slowly and persons can live for long period at heights of 15,000 to
20,000 feet without ill effects. This adjustment of the body is called ‘Acclimatization.’
The physiological changes are:
• Increase in rate and depth of respiration (to minimize the
difference between the oxygen of the air andoxygen of the blood).
• Increase in the hemoglobincontent of the blood.
• Increase in the cardiac output.
II.Effects of Increased Atmospheric Pressure:
This occurs in low altitudes. The effects are best observed in persons Working in diving
bells, compressed air chambers (Caisson’s), etc. and the symptoms produced is known
as ‘Caisson’s disease,’ where in the personexposed to high pressure, the gases in
the air such as oxygen, carbon dioxide andnitrogen are dissolved in the blood and tissues,
depending upon their partial pressures and the whole body is thus saturated with air.
Decompression sicknes:
As a rule, the workers do not suffer while they are in the caisson but grave symptoms
occur after they return to the outside air. It is called ‘Decompression sickness,’
characterized by euphoria, sensation of increased strength, respiration becomes
deeper andquicker and the heart becomes stronger and slower. These may be followed by
nasal voice, disturbance in hearing, changed sense of smell or taste, rarely hemorrhages from
the mouth, tympanic cavity and even from the lungs.
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2.AIR TEMPERATURE:
Not only it has a direct impact on the health of the individual but also it has an important
bearing in the natural history of certain diseases, especially vector borne diseases
like malaria, filariasis, Kyasanur forest disease, Japanese encephalitis, etc. For example, the
malarial parasites cease to undergo development in the stomach of the female
anopheline mosquito when the mean temperature remains below 16°C.
Optimum air temperature for the development of malarial parasites is between 20 and30°C,
i.e. 68 and 86°F.
Measurement of Air Temperature:
Air temperature is recorded by using thermometers. There are two types—Mercury
thermometer and Spirit (or alcohol) thermometers.
Effects of Temperature:
This can be studied under two heads—of high temperature and of low temperature.
A)Effects of High Temperature:
 Local effects—are blackening of skin, prickly heat (i.e. Heat rash or miliaria rubra), sun
burn anddermatitis.
 General effects—are heat exhaustion, heat cramps and heat stroke.
(Heat–strain:
The patho-physiological effects of heat on body system is called ‘Heat–strain’.)
I.Heat exhaustion:
This term includes heat syncope, water depletion exhaustion andsalt depletion
exhaustion.
 Heat syncope: It is characterized by giddiness and fainting due to pooling of blood in
the lower limbs following prolonged standing in the hot sun, Which is common among
soldiers.
 Water depletion exhaustion: It is characterized by excessive loss of water due
to profuse sweating. If water is not replaced, it leads to a reduction of intracellular fluid,
resulting in excessive thirst, oliguria, oligemic shock andeven in death.
 Salt depletion exhaustion: Along-with the perspiration, there will be a loss of sodium
chloride, leading to reduction in the extra-cellular fluid and signs of dehydration.
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4. II.Heat cramps:
This is another acute clinical condition resultingfrom exposure to heat. It is
characterized by sudden and severe painful, spasmodic contractions of the skeletal
muscles, due to loss of sodium and chloride from the body.
III.Heatstroke (Sun stroke):
It is usually due to radiant heat from the sun. It is characterized by very high body
temperature of above 106°F, rapid pulse, rise of blood pressure,dry andhot skin,
delirium, convulsions, partial or total unconsciousness, stupor, coma followed by death.
B)Effects of Decreased Atmospheric Temperature:
 General effects: Initially, there will be shivering and tensing of the muscles resulting in rise
of BP, pulse rate and respiration rate followed by decrease in BP, pulse rate and respiration
rate. Later, there will be hemoconcentration, oliguria and muscular weakness. With
hypothermia at 80°F, coma sets in. At 75°F, death occurs following ventricular
fibrillation.
 Local effects: Local changes occur in the extremities (hands and feet).
The conditions are:
I. Acute transient inflammatory reaction.
II. Trench foot.
III. Frost bite
I.Acute transient inflammatory reaction:
When the body is exposed to cold temperature, there will be
Vaso-constriction of the superficial blood vessels followed by intermittent vaso-dilatation. This is
called ‘Hunting’ phenomenon, due to the release of chemical substance locally in the tissues.
There will be pain, numbness and loss of sensation.
II.Trench foot (or immersion foot):
It is so called because it used to be common among those soldiers, who used to stand in
trenches for long periods during Ist World-War. Prolonged exposure to cold initially
results in acute transient inflammatory reaction, later followed by vaso-dilatation, transudation,
hemoconcentration, platelet conglomeration, tissue edema and gangrene may follow.
III.Frost bite:
This occurs when exposed to temperature of 0 to – 5°C. There is actually
freezing of the tissues and crystals of ice are formed between the cells. The skin
appears pale, dull, opaque andyellowish.
3.HUMIDITY:
Atmospheric humidity means the moisture content of the air.
Atmospheric humidity ∝
eTemperatur
1
5
(Dew point:
The temperature at which the moisture precipitates is called ‘Dew point.’)
Humidity may be expressed as absolute humidity or relative humidity.
-Absolute Humidity:
It is the actual amount of moisture (or water vapor) in an unit
volume of air.
-Relative Humidity:
Relative humidity (RH) is the percentage of moisture present n the air,
complete saturation being taken as 100. Greater the relative humidity, the nearer the
air to saturation.
Measurement of Humidity:
The humidity of the air can be measured by an instrument called ‘Hygrometer’, of which
there are two kinds—namely direct and indirect hygrometers.
Direct hygrometers are Danniell’s Hy, Regnault’s Hy and Dine’s Hy.
Indirect hygrometers are dry and wet bulb hygrometer, Sling psychrometer and Assmann
psychrometer.
Effect of humidity on human body:
I.Health Risks of High Humidity:
When the air has a high moisture content, as is the case in humid weather, this sweat
cannot evaporate, leaving our bodies feeling hot and sticky. To cool off, our bodies must work
even harder.It can contribute to feelings of low energy and lethargy. In addition, hyperthermia,
or over-heating as a result of your body’s inability to effectively let out heat, can negatively
impact your health in conditions of high humidity.
II.Health Risks of Less Humidity:
Eyes become dry and irritated, skin gets flaky and itchy and the low humidity inflames and
dries out the mucous membrane lining the respiratory tract. As a result, the risk of cold, flu and
other infections is substantially increased.
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5. 4.AIR MOVEMENT:
Even with disruptions like weather fronts and storms, there is a consistent pattern to how air
moves around our planet’s atmosphere. This pattern, called atmospheric circulation, is caused
because the Sun heats the Earth more at the equator than at the poles. It's also affected by the
spin of the Earth.
Measurement of Air Movement:
The best instrument used to record the velocity of air and also the pressure of the wind is
Robinson’s wind anemometer.
Effect of AIR Movement:
The way the air moves affects the weather, because winds move heat and cold
temperatures as well as moisture from one place to another, transporting conditions from one
geographical zone to another. The way winds pass each other, and the direction they move,
also affects what weather a region will see on any given day.
5.Rain Fall:
Rain is liquid water in the form of droplets that have condensed from atmospheric water
vapor and then become heavy enough to fall under gravity.
Measurement of Rain Fall:
The standard instrument for the measurement of rainfall is the 203mm (8 inch) rain gauge.
Effects of Rain Fall:
Heavy rainfall can lead to numerous hazards, for example: flooding, including risk to human
life, damage to buildings and infrastructure, and loss of crops and livestock. landslides, which
can threaten human life, disrupt transport and communications, and cause damage to buildings
and infrastructure.
When little or no rain falls, soils can dry out and plants can die. When rainfall is less than
normal for several weeks, months, or years, the flow of streams and rivers declines, water
levels in lakes and reservoirs fall, and the depth to water in wells increases.
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6. 6.Precipitation:
In meteorology, precipitation is any product of the condensation of atmospheric water vapor
that falls under gravity from clouds. The main forms of precipitation include drizzle, rain, sleet,
snow, ice pellets, graupel and hail.
Measuremet of precipitation:
Precipitation is measured as the amount of water that reaches horizontal ground or the
horizontal ground projection plane of the earth's surface, and is expressed as a vertical depth of
water or the water equivalent of solid precipitation.
Effects of Precipitation:
Global Climate Change. comes from precipitation. Too little precipitation can result in dry
soil, shallow streams, and shortages of municipal water supplies. However, too much
precipitation can also have a negative impact on human activities, business and industry,
agriculture, and the environment.
7.Visibility :
In meteorology, visibility is a measure of the distance at which an object or light can be
clearly discerned. It is reported within surface weather observations and METAR code either in
meters or statute miles, depending upon the country. Visibility affects all forms of traffic: roads,
sailing and aviation. Meteorological visibility refers to transparency of air: in dark,
meteorological visibility is still the same as in daylight for the same air.
Measurement of visibility:
Visibility is limited to about 296 km.One classical method to measure visibility is to measure
how much light that is transmitted from a light source to a receiver located a distance- for
instance 50 meters away. In foggy weather less light (compared to during clear weather) will
reach the receiver because of the scattering along the ray path.
Effects of Visibility:
Visibility is a measure of how well an observer can view a scene. This includes how far
one can see in the atmosphere as well as the ability to see the textures and colors of the
scene.Unfortunately, these views are sometimes obscured by haze, which consists of fine
particles and gaseous air pollution in the atmosphere. Although haze does occur naturally,
due to things such as dust and wildfire smoke, it is primarily caused by air pollution from
anthropogenic sources.
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7. 8.Cloudiness :
The state of being cloudy (e.g. weather). Expect considerable cloudiness with occasional
rain showers.
Measurement of Cloudiness:
In meteorology, an okta is a unit of measurement used to describe the amount of cloud
cover at any given location such as a weather station. Sky conditions are estimated in terms of
how many eighths of the sky are covered in cloud, ranging from 0 oktas (completely clear sky)
through to 8 oktas (completely overcast).
Effects of cloudiness:
Effects of Cloud Cover: on forecasted temperatures. During the day, the earth is heated by the
sun. If skies are clear, more heat reaches the earth's surface. This leads to warmer
temperatures.
9.Sunshine Duration:
Sunshine duration is the length of time that the ground surface is irradiated by direct solar
radiation (i.e., sunlight reaching the earth's surface directly from the sun).
Measurement of Sunshine Duration:
Measurement is performed by instruments called sunshine recorders. For the specific
purpose of sunshine duration recording, Campbell–Stokes recorders are used, which use a
spherical glass lens to focus the sun rays on a specially designed tape. When the intensity
exceeds a pre-determined threshold, the tape burns.
Effects of sunshine duration:
Energy from the Sun is very important to the Earth. The Sun warms our planet, heating the
surface, the oceans and the atmosphere. This energy to the atmosphere is one of the primary
drivers our weather. Our climate is also strongly affected by the amount of solar radiation
received at Earth.
The Sun is the source of most of the energy that drives the biological and physical
processes in the world around us—in oceans and on land it fuels plant growth that forms the
base of the food chain, and in the atmosphere it warms air which drives our weather.
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