Precipitation and its classification

1. AGR X 101
PRINCIPLES OF AGRONOMY AND AGRICULTURAL
METEOROLOGY
Topic:
Gowtham, G.
2020713029
I- Diploma Horticulture (2020 Batch)
Precipitation and its classification

2. Precipitation
• Precipitation is all form of water that reaches the earth surface form
atmosphere.
• Precipitation can be in solid form or in liquid form.
• The usual forms of precipitation are rainfall, snow, hail, frost, dew etc.,
• It is the most important phase in the hydrological cycle.

3. Precipitation

4. FORMATION OF PRECIPITATION:
Formation of precipitation needs following conditions and processes
Presence of moisture:
Water vapors’ presence in the atmosphere only conditions for
precipitation.
Condensation process:
Condensation nuclei present in sufficient quantity condense to form
droplets due to a decrease in atmospheric temperature
Cooling process:
Cooling leads only to fog formation

5. CLASSES OF PRECIPITATION
• Precipitation which forms in the high atmosphere and which falls
from vegetation and soil surface (from clouds)
• Horizontal precipitation near ground surface (fog ppt) which
originates in the atmosphere near the ground
• Precipitation such as dew and rime, which develop at the ground
surface itself.
On the basis of Origin:
Liquid (rainfall, dew, drizzle, etc)
Solid (snowfall, hail, storm, etc)
On the basis of States:

6. On the basis of States
• Dew: water droplets which are deposited by direct
condensation
• Fog: layer of minute drops of water ice crystals
suspended in the atmosphere
• Mist: thin fog in which horizontal visibility is greater
than 1 mm where water vapors are smaller than fog
Liquid form of precipitation

7. • Snow: –Precipitation in the form of ice crystals results from
sublimation i.e. from water vapors directly to ice.
• Hail: – is precipitation in form of balls of ice crystals over 5mm
diameter formed by alternate freezing and melting
• Glaze: – is the ice formed when rain freezes as it comes in contact
with the cold object at the earth
• Frost – is light feathery edge like ice crystals which are
deposited to when the dew point temperature is below freezing
point.
• Grapple: – It is a form of snow in soft pellets having Non –
uniform surface.
Solid form of precipitation

8. • Precipitation occurs when the moist air mass undergoes the
process of condensation.
• This process occurs when the air is cooled and saturated.
• This process of cooling the air mass occurs only when the air
mass moves up to the higher altitudes.
The air mass can be lifted to higher altitudes primarily by three
methods
1. Cyclonic Precipitation
2. Convective Precipitation
3. Orographic Precipitation
Types of precipitation

9. A cyclone is a region in the atmosphere that has a large low pressure
having circular wind wave.
The cyclonic precipitation is caused due to the movement of moist air
mass
This precipitation is caused due to the expansion of air near the frontal
surface.
Cyclonic Precipitation

10. • The air above the land area gets heated up due to some cause.
• Most of this warmer air rises up, cools and precipitates. Convective
precipitation is showery by nature.
• This type of precipitation occurs in varying intensities
Convective Precipitation

11. Orographic precipitation
• Results from the mechanical lifting of warm moist air
over mountain barriers.
• It is causal by lifting of air when crossing mountain
range laying across their paths.
• Much of the rain in the outer Himalaya hills both during
the summer monsoon and in winter.