2. Hydrometeorology
• Hydrometeorology is branch of science which deals with the
water in the atmosphere.
• The recent and broad definition
• It is the part of hydrology which concerns with atmospheric
and surface water.
Hydro-meteorological Instruments
• Maximum and Minimum Thermometer
• Soil thermometer
• Psychrometer
• Wind wanes and anemometer
• Evaporimeters
• Rain gauge
• Fortin’s barometer
• Pyranometer and radiometer
• Sunshine recorder
3. • Maximum and Minimum Thermometer: It indicates the lowest and
highest temperature between two stations.
• Soil thermometer: it is used to measure the soil temperature.
• Psychrometer: A stationary psychrometer is used to measure
humidity (air moisture) at hydro-meteorologial station.
• Wind wanes and anemometer: It is used to measure the wind
velocity. This velocity is measured by wind wanes and cup-
anemometer.
• Evaporimeters: they are instruments used to measure evaporation
i.e water that escapes from land and water bodies into the
atmosphere.
Commonly used Evaporimeters are Piche Evaporimeters, Colorado
sunken pan, US geological survey floating pan, ISI standard pan
and US weather bureau class A pan. Most commonly used eva-
porimeters in India is US weather bureau class A pan eva-
porimeter.
4. • Fortin’s barometer: It is the instrument used to measure the
pressure exerted by the atmosphere. It consists of inverted
U-tube filled with mercury kept in a cistern. It is also
measured by aneroid barometer.
• The instruments which records the variation of pressure
with time is called barograph.
• Pyranometer and Radiometer: These are the instruments
used to measure the radiation. It is used to measure the
short wave solar radiation, both direct and diffused,
reaching the Earth’s surface.
• The total incoming and outgoing radiation is also measured
without filtering effect of the lime glass. This device is
called radiometer.
• Sunshine recorder: It is the instrument to measure the
bright sunshine in a day.
5. Vertical Structure of the atmosphere
Longwave,
Latent heat,
Sensible heat
Ultra-violet
sunlight
Solar winds,
Cosmic rays
7. • Troposphere: From the earth's surface to 11-12 km above, temperature decreases with
height. It contains above 75% of the mass and all moisture and dust of the atmosphere.
The degree of static stability is low and air is often unstable.
• Tropopause: it is the layer above the troposphere. Its height varies from 8km at poles
and 10 km over the equator. Temperature is almost constant in this layer.
• Stratosphere: It is the third layer above tropopause varying its altitude from 10km to
45km. Here temperature increases, i.e lapse rate is positive. It contains very little
moisture and dust.
• Mesosphere: the temperature is initially high and decreases with increase of altitude.
Initial high temperature is due to selective absorption of ultraviolet radiation from the
sun.
• Ionosphere: this major layer is normally at about 80km above the earth. Pressure is low
at this layer.
Ionosphere is divided into number of layers with different electrical properties and
varying intensities. The layer merges gradually into the outer most shell, i.e exosphere.
Ionosphere is also called thermosphere.
The two layers tropopause and stratosphere together called Ozonosphere.
8. Mission of National Weather Service
• The National Weather Service provides weather,
water and climate data, forecasts and warnings
for the protection of life and property and the
enhancement of national economy.
