This document discusses different types of precipitation including rain, drizzle, snow, hail, snow pallets, and sleet. It explains that precipitation forms through the process of evaporation, cooling, condensation, and growth of water droplets. There are three main types of precipitation: convective, orographic, and cyclonic. Orographic precipitation occurs when moist air is forced upwards over rising terrain such as mountains.

1. Presented by:- Prof. S. R. Satpute
Assistant Professor
ICEM

2. ▣ In meteorology, the term precipitation is any product
of the condensation of atmospheric water vapour that
falls under gravity.
▣ It includes all forms of water coming from the
atmosphere to the earth.
▣ Precipitation is the one of the major element of
hydrology after it falls on the ground because it is the
source of water on the earth.
▣ Precipitation can fall in either liquid or solid phases, or
transition between them at the freezing level.

3. ▣ The process of formation of
precipitation works in four
stages:
Evaporation Process
Cooling Process
Condensation Process
Growth of droplet Process

4. ▣ It depend on formation of precipitation, various geographic
conditions and various climateconditions.
▣ There are mainly three types of precipitation:
1. Convective Precipitation
2. Orographic Precipitation
3. Cyclonic Precipitation

5. ▣ When evaporation happen, unsaturated air near the Earth’s
surface is carried to higher levels.
▣ Pressure decrease with altitude and reduction of pressure causes
an expansion on the air and air absorbs more water moisture.
▣ The moisture air moves up. Air cools and condenses with height
due to lower temperature.
▣ That is referred to as “dynamic
▣ cooling” and condensed air is formed as clouds. (Cooling and
Condensation Process)
▣ Condensation is not necessarily cause precipitation. Water droplets
accumulate and larger droplets collide and combine with smaller
droplets.
▣ That causes a further increase droplet size and when the water
droplets heavy enough, fall as rain due to gravitational force. (Growth
of Droplets Process)

8. ▣ This precipitation occurs when moist air is forced upwards over
rising terrain, such as a mountain.
▣ Heated air near the ground expands and absorbs water moisture.
The moisture air moves up. Then mass of air is pushed by wind
are forced by a topographic barrier.
▣ Air rise to higher elevations and expansion, cooling and
precipitation process take part with one by one.
▣ That process is referred as “orographic precipitation”.
▣ Precipitation occurs on windward side of barrier.
▣ On the leeward side of barrier, the clouds are lighter without the
weight of the water. Moisture is removed by barrier and air
descent. Therefore, rain shadow can be observed on leeward side.
▣ Because of the orographic precipitations, a moisture climate can
be observed at the windward side and a more arid climate can be
observed at leeward side due to lack of rainfall.

10. ▣ As the shape of the Earth is geoid. Therefore, sunlight
comes to the Earth surfaces with different angle and
causes an uneven heating on the Earth surface.
▣ Maximum heat from the sun is received by the regions
close to equator and the air around that region gets warm.
▣ On the other hand apart from the regions close the equator,
air gets cold.
▣ These warm and cold air flow and collide in some region
with the effect of winds.
▣ In addition , during seasons the land can be heated more
than the sea or vice versa that also causes the collide of
the warm and cold air.

11. •Warm Front and Cold Front (Frontal or non-frontal precipitation):-
The uneven heating of the Earth’s surface by the sun can result as high
and low pressure regions.
•The boundary between air masses with different pressures is called as a
front.
•If warm air moves over cold air, it is called a warm front.
•. If cold air moves under warm air, it is called as a cold front.
•Precipitation along a warm front, warm air mass rise up on a slope
over the colder air mass, because warm air has less density than the cold
air.
•Warm air cools during rising up and it moisture gets condensed. That
produces clouds and precipitation is observed.
•Precipitation along a cold front, cold air mass wedges into the warmer
air mass.
•Warm air is lighter than cold air and therefore, warm air is lifted upward.
•Warm air cools during rising up and it moisture gets condensed.
•That produces clouds and precipitation is observed. Cold fronts moves
faster and produce high intensity rainfalls.
•As a result, a precipitation is caused by lifting of an air mass due to the

13. ▣ Rainfall takes place in many different forms in the regions
located in the middle latitudes.
▣ Typical characteristics of various forms of precipitation are
explained below:
1. Rain:- These are water droplets mostly size larger than 0.5
mm in diameter.
2. Drizzle:- These are tiny water droplets of size between 0.1 to
0.5 mm which fall with such slow settling rates that they
occasionally appear to float.
3. Snow:- It is the type of precipitation which results from
sublimation that is water vapors directly changes to ice.
▣ It falls as white or translucent ice crystals often
agglomerated into snow flakes.
▣ The specific gravity of snow is often taken to be 0.1

14. 4. Hail:- These are the precipitations in the forms of lumps of
ice.
▣ These hailstones are produced in convective clouds mostly
cumulonimbus.(Very tall and large clouds i.e {5-13 km} in
appearance)
▣ These may be conical, spherical, spheroidal or irregular in
shape.
▣ The sizes of hailstones may be anything more than 5 mm.
▣ The specific gravity of hailstones is about 0.8
5. Snow Pallets:- These are sometimes called as soft hail too.
▣ These are more crisp and are of 2-5 mm of size.
▣ Due to their crispness upon hitting the hard ground, they
oftenly breaks up.

15. 6. Sleet:- When the rain drops fall through the layer of
sub-freezing air near the earths surface, the rain-drops
gets frozen into ice stage.
This is called as Sleet or Grains of ice.
Rain Drizzle

16. Snow
Hail
Snow
Pallets
Sleet