In atmospheric aerosol cloud drops form on which function as condensation nuclei or condensation nuclei . Speed drops formation is determined by the number of condensation nuclei . The process by which water drops from vapor phase condensation formed on the core pengintian called heterogeneous . The formation of drops of water from the vapor phase in a pristine environment that requires highly saturated conditions ( supersaturation ) is called homogeneous pengintian . Pengintian ie homogeneous freezing of pure water will only occur at temperatures below -40 ° C. However, the presence of aerosols as condensation nuclei then freezing can occur at temperatures only a few degrees below 0 ° C.Condensation nuclei are solid particles or liquid that can be dust , smoke , sulfur dioxide , sea salt ( NaCl ) or other microscopic objects which are hygroscopic , with a size of 0.001 to 10 micrometers .Briefly in the formation of cloud condensation process is as follows :
Upward moving air will experience adiabatic cooling so nisbinya humidity ( RH ) increases , but before the RH reaches 100 which is about 78 ondensasi has begun on a larger condensation nuclei and active . RH changes due to the addition of water vapor by evaporation or decrease the saturation vapor pressure through cooling .
Drops of water then began to grow into cloud drops when RH approaches 100 Since water vapor has been used by the cores larger and smaller core not less active role , the volume of cloud drops formed much smaller than the number of condensation nuclei .
Cloud drops formed generally have a radius of 5-20 mm . Drops of this size will fall at a speed of 0.01 to 5 cm / s is the speed of the air flow upward so much larger cloud drops will not fall to the earth . Even if the humidity is less than 90 aka the drops will evaporate . To be able to fall to the ground without yawning , we need a larger drop of around 1 mm (1000 micrometers ) , because only by the size of the drops so they can beat the upward air movement ( Neiburger , et . Al . , 1995) .
So the difference between clouds and drops of rain drops is on its size . If a cloud is growing continuously , then the peak will pass through clouds 0 ° C isotherm But most of the cloud droplets are still liquid and part solid ice crystals or if there is a freeze core . If there is no freeze core , the cloud droplets remain liquid until the temperature reaches -40 ° C even lower.Clouds that were targeted in the activities of artificial rain is the kind of clouds Cumulus ( Cu ) are active , Dangan characterized as cauliflower shape . Cumulus clouds occur due to convection process . In more detail Cumulus clouds are divided into 3 types , namely : Strato Cumulus ( Sc ) Cumulus clouds are emerging ; Cumulus , and Cumulonimbus ( Cb ) Cumulus clouds are very large and may contain some Cumulus clouds are merged into one .Cold and Warm Clouds cloudsBased on the physical environment temperature of the atmosphere in which the cloud develops , differentiated cloud cloud top (cold cloud ) and cloud warm (warm cloud ) . Cold cloud terminology is given to all its parts are clouds on atmospheric environment with temperatures below freezing ( < 00C ) , while the warm clouds are clouds that all parts are above freezing ( > 00C ) .Cold clouds are clouds that are mostly in the middle and high latitudes , where the air temperature near the ground surface alone can reach values < 00C . In the tropics as well as in Indonesia , the air temperature near the ground surface around 20 - 300C , has a cloud base temperature of about 180C . However, the cloud tops can penetrate deep into the upper surpass freezing , so most of the cloud is warm cloud , some on top of a cold cloud . Such clouds are called clouds mix ( mixed cloud ) .Process of Rain In Cold CloudsIn the cold rain clouds starting from the ice crystals . that develop enlarged in two ways water vapor deposits or supercooled water ( supercooled water ) directly on ice crystals or through incorporation into granular ice . The existence of ice crystals is very important in the formation of rain clouds cold , resulting in the formation of rain clouds cold is often called the ice crystals .As the air rises higher into the atmosphere , forming water droplets , and clouds formed . When it comes to a certain height axis are below freezing , it freezes into a cloud of tiny ice crystals . Surrounding air is not so cold that freezes the last crystal . Thus grew and became crystal snowflakes . When it becomes too heavy , the snow fell . When through the air warmer, the snow was melting into rain . In winter snow falls without melting .
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