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Water-Hail
Hail is the crystalized particles or drops
of water pieces of ice which sometimes
has a regular shape and is often seen in the
shape of oval.Pyramid,sphere,and semisphere.
The outer surface of the hail is sometimes
smooth and sometimes rough and bumpy.
Hailstones usually get their final shape in
several stages.When the first step in the
production of hail,like that of the rain is
formed,as a result of a vertical movement of
a current of air upwards,the tiny particles
of water in the current quickly reach the
freezing point and immediately freez.As these
frozen particles move downwards,other water
and ice drops attach to them and hence they
grow.But when they reach the lower levels of
clouds,because of the rising of a current of
the air inside the clouds which take place
as a result of certain processes,the frozen
particles move upwards again.This cycle
repeats until the current of the air upwards
can support the weight of the particles,at
this time the hails leave the clouds and
the precipitation happens.
Hail generally takes place in clouds of
cumulonimbus type,because these clouds have
a very high vertical extension and inside
them swift horizontal movements,whose speed
sometimes gets to twelve to thirty m/s,are
seen.These are suitable environments for the
formation and the development of hailstones.
Hailstones are divided into three groups
according to size and shape :
1.smooth hail frost is made of white icy
particles which are relatively round and
opaque ; their structure is like that of
snow and they are often in the shape of
a cone , their diameter is varies from 2
to 5 millimeters.The smooth hail cracks and
smashes as soon as it gets to the ground.In
most cases this kind of hail appears in the
form of shower in zero degrees temperatures
along with snow or before the snow.
2.tiny hail icicle is made of spherical
semi-transparent particles which on rarely
conic and their diameter varies from 2 to 5
millimeters.This kind of hail forms when air
temperature is several degrees below zero on
the centigrade scale.
3.hail is formed from icy particles whose
diameter varies from 5 to 50 millimeter and
sometimes even more because of the frequent
cycles and steps in which hail develops,it
consists of transparent,semi-transparent,
opaque and milky layers.It often hails in
the form of showers in spring.
Each hailstone usually consists of three
sections :
A - a white core which is usually like
a snowball,B - a great number of white
fiber-like layers which are seen around
the core,C - a thin froze shell which
surrounds the hailstone this shell is
sometimes missing .
Hail temperature is usually below zero
degrees centigrade,but it might occasionally
reach that , it which case it carries some
water.It usually hails in spring or other
transitional seasons of the year,because
during these seasons severe atmospheric
disturbances make the condition suitable for
the formation of hail.
