Different Forms Of Condensation And Clouds
Condensation is the transformation of a physical state of matter from a gas to a liquid, and it is the inverse of recognized. Condensation comes in a variety of forms. Dew- Dew is water in the form of droplets that forms on thin, exposed objects due to condensation in the morning or evening. As the exposed surface cools by radiating heat, atmospheric moisture condenses faster than it can evaporate, forming water droplets.
1. Frost is a thin layer of ice that forms on a solid surface when water vapor from an above freezing atmosphere comes into contact with a solid surface that is below freezing, resulting in a phase change from water vapor to ice as the water vapor reaches the freezing point.
2. Dew occurs when the dew point temperature is above freezing, while frost occurs when the temperature is below freezing.
3. Fog is a visible aerosol made up of small water droplets or ice crystals suspended in the air near the Earth's surface. Fog is a low-lying cloud that looks a lot like stratus and is heavily influenced by nearby bodies of water, topography, and wind conditions.
Clouds:
• Clouds are made up of suspended water droplets or ice crystals in the air. A visible aggregation of minute water droplets and/or ice particles in the air, usually above ground level, is referred to as a cloud. The diameter of these particles ranges from 20 to 50 microns.
• One millionth of a meter is referred to as a micrometer. Each cloud particle is formed on a condensation nucleus, which is a tiny center of a solid particle. This nucleus has a diameter ranging from 0.1 to 1 micron.
• The physical processes taking place in the atmosphere are very clearly reflected in clouds. As a result, they serve as weather indicators.
• Condensation produces clouds, which are the most common form of suspended water droplets. These would look exactly like fog if they were brought down to the ground. A fog raised above the ground, on the other hand, would appear to be a cloud. When the air above the ground is cooled below its dew point or extra moisture is added, clouds form.
• Many processes can cause cooling, but rising air is usually involved in their formation. The clouds will form in layers if the air movement is generally horizontal, and these are known as stratiform clouds.
• Cumuliform movements are those that are vertical in nature. Because convectional currents are limited to the troposphere, the troposphere is home to nearly all clouds. Although very high clouds can be found in the lower stratosphere, they can also be found in the upper stratosphere.
Classification of Clouds
• Clouds are categorized by their height, shape, color, and light transmission or reflection. Cirrus (feathery or fibrous), stratus (stratified or in layers), and cumulus are the three basic cloud types (in heaps). At different elevations, different types of clouds are either pure forms or modifications and combinations of pure forms.
• The cloud will be thin and the word ‘alto' will be prefixed to its form if it occurs above its normal height of 1950m. If a cloud is associated with rain, it is prefixed or suffixed with the word "nimbus," which means "rain." Clouds are classified into ten distinct types, according to the World Meteorological Organization's International Cloud Atlas from 1956.
1. Cirrus: These are the highest, most delicate, detached, fibrous, feathery clouds with no shading. Before sunrise or after sunset, they appear bright red or orange. They are made up of thin ice crystals or needles rather than water droplets. A halo is created when the sun or moon shines through these clouds. There is no precipitation from these clouds.
2. Cirrostratus: These clouds appear as a thin whitish veil, often covering the entire sky or a large portion of it. These are extremely thin, giving the sky a milky white hue. Ice crystals are used to make these. Halos are caused by Cirrostratus clouds, which are common but do not blur the outline of the sun or moon.
3. Cirrocumulus: These are small white flaky globular masses that cover small or large areas of the sky and have no shading. They are frequently arranged in bands or fused into waves or ripples that resemble sand on a beach.
4. Altostratus: These clouds are bluish or greyish white cloud sheets that cover the entire sky or a large portion of it. They can appear in broad, uniform bands at times. The sun could be completely hidden or shine through thin watery conditions. Altostratus do not have halo effects. Water droplets make up these clouds, which are often super-cooled to temperatures well below freezing. Fine drizzle or snow may fall as precipitation.
5. Altocumulus: Individual or in groups, these clouds form as elliptical, globular units. Individual altocumulus clouds are often elongated elliptical units with little or no vertical doming. Halos do not form in altocumulus clouds.
• The undersides of their bodies are darkly shaded. These are frequently made up of liquid droplets that have been super cooled. This type of cloud can appear at multiple levels at the same time.
6. Stratus: Stratus is a grey cloud sheet or layer that can produce drizzle, ice prisms, or snow grains. When the sun shines through the cloud, the outline of the sun can be seen.
• These do not cause halo effects. Stratus clouds are a type of cloud that has no discernible shape or structure and completely cover the sky.
• Stratus clouds become thicker and darker when they are overlain by higher altostratus clouds.
7. Nimbostratus: These are cloud sheets that are thick, dark grey, and shapeless, with regular broken clouds beneath and around them. It's a low-lying cloud that could be thousands of feet thick. It's a cloud that rains, snows, or sleets but never includes lightning, thunder, or hail. It differs from the stratus type because it is darker.
8. Stratocumulus: These are large, heavy rolls or elongated globular masses arranged in long grey parallel bands that usually cover the entire sky or at least a large portion of it.
• They are frequently formed by the flattening of cumulus clouds, which may be arranged in bands or develop as a continuation of low-altitude altocumulus.
• The stratocumulus in this case appears darker, lower, and heavier than the related altocumulus.
9. Cumulus: These are dispersed white clouds with sharp outlines that develop vertically in the form of domes or towers, with bulging upper parts that resemble cauliflower. These clouds are mostly brilliant white where the sun shines; their base is dark and horizontal.
• The tops of strong convective currents are represented by these clouds. They are most noticeable in the summer, but they can appear at any time of year. They are most commonly seen during the day over land areas and then dissipate at night.
• They only produce a small amount of precipitation. They frequently signal the onset of cumulonimbus, a heavier shower cloud.
10. Cumulonimbus: These clouds develop from cumulus clouds that have grown into massive towering clouds with a vertical range of 3 to 8 kilometers from base to top.
• In tropical areas, they can reach a height of 16 kilometers. When these clouds reach this height, they form the well-known thunderstorms. A cumulonimbus cloud is a tall cloud that spreads out on top to form an anvil head.
• Heavy rain, thunder, lightning, hail, and tornadoes are all associated with this cloud type. A flat top (anvil head) and a flat base characterize this cloud. As the condensation within it grows, it darkens and obstructs the sun. Squally, gusty, and short-lived thunderstorms are caused by the great thunderhead.
Summer afternoon thunderstorms in the middle and lower latitudes are very common. A real shower and a sudden darkening of the sky can easily identify this type of cloud.
Different Forms Of Precipitation
• Condensation of water vapors in the air mass causes precipitation. Due to adiabatic cooling, the ascending air mass with a sufficient amount of water vapors becomes saturated. Clouds are formed by the condensation of water vapors. There are updrafts and downdrafts in every cloud.
• The updraft determines the development and height of the clouds. The higher the cloud rises, the stronger the updraft. The strength of the updraft decreases as the liquid water level rises, while the downdraft rises. Precipitation is produced as a result.
• Despite the fact that all clouds contain water, some produce precipitation and others do not. Precipitated moisture falls from the clouds in some cases, but it evaporates in the atmosphere before reaching the earth's surface.
• Precipitation occurs only when cloud droplets or ice crystals grow large enough to overcome the atmosphere's updrafts. It means that in a cloud from which precipitation falls, some unique processes are at work.
In the middle latitudes, precipitation comes in a variety of shapes and sizes. The following are the typical characteristics of various types of precipitation:
1. Rain: It is made up of water drops that are mostly larger than 0.5 mm in diameter.
2. Drizzle: These are tiny water droplets ranging in size from 0.1 to 0.5 mm that fall at such a slow rate that they appear to float on occasion.
3. Snow: This is the type of precipitation that occurs as a result of sublimation, in which water vapor transforms into ice. It often agglomerates into snowflakes as white or translucent ice crystals. Snow's specific gravity is commonly assumed to be 0.1.
4. Hail: Hail is a type of precipitation that comes in the form of ice lumps. Convective clouds, mostly cumulonimbus, produce hail stones. They can be conical, spheroidal, or irregular in shape. Hail stones can be as large as 5 mm in diameter. Hail stone has a specific gravity of about 0.8.
5. Pallets for Snow: Soft hail is another name for them. Snow pallets are smaller and crisper, ranging in size from 2 to 5 mm. When they hit the hard ground, their crispness causes them to break up.
6. Sleet: When raindrops fall through a layer of sub-freezing air near the earth's surface, they freeze to the ice stage. It's known as sleet or ice grains.
Types of Rainfall
There are three different types of rain:
1. Orographic Precipitation
2. Precipitation caused by convection.
3. Frontal Precipitation is a type of precipitation that occurs in the front of the body.
1. Orographic Precipitation
• When a moist air mass rises on the mountain's windward side, this type of precipitation occurs. Because the moist air mass is lighter than the dry air mass, buoyancy forces push the moist air mass down the mountainside, where it cools at the dry adiabatic rate. When the air mass is sufficiently cooled, it becomes saturated, and condensation begins. As a result, clouds begin to form and the lifting condensation level is reached.
• The air cools adiabatically when the mountains act as a barrier to the flow of air mass, resulting in clouds and precipitation. Orographic precipitation is the term for this. On the windward side of the mountains, this type of precipitation occurs.
• However, due to the descending air mass, which is heated at a dry adiabatic lapse rate, precipitation on the leeward side drops abruptly. As the air mass descends, it becomes dry and hot.
• The clouds on the leeward side vanish as a result. As a result, dry areas always exist on the mountain's leeward side. Rain shadow zones are what they're called. This is because on the windward side, moist air predominates, while on the leeward side, warm dry air predominates.
• In India, the south-west monsoon brings heavy rain to the windward slopes of the Western Ghats, while rain shadow areas abound on the leeward side. On the windward side, precipitation increases steadily until it reaches a certain height, after which it begins to decrease. This is referred to as rainfall inversion.
2. Convectional Precipitation
This type of precipitation is only possible if two conditions are met:
a. Intense heating of ground surface
b. Abundant supply of moisture.
• Solar radiation is the primary source of heat used to create air convection currents. When the surface is heated unevenly, this process begins. The air above the bare soil will become warmer during the day than the air above the adjacent forest. Warm air has a lower density than cold air. Air is forced to rise due to the creation of convection currents. The air is adiabatically cooled, and its temperature drops as it rises. As long as the air mass is warmer than the surrounding air, it will continue to rise.
• As the rising air mass cools adiabatically, it becomes saturated. Condensation begins to form, and the rising air column transforms into a puffy cumulus cloud.
• The cloud will develop into a dense cumulonimbus cloud if the convection continues to be strong. This type of cloud is always associated with heavy rainfall.
• Warm-weather precipitation of the convective type is a common occurrence. Thunder, lightning, and strong surface winds are commonly associated with it. Hailstorms are sometimes associated with it. Low latitudes and temperate zones experience this type of precipitation.
• It usually happens in the evenings during the summer months. This type of precipitation occurs in the mountains and is characterized by heavy showers.
• Consistent rain is more effective for crop growth than convective precipitation. Because runoff is at its highest in this case, there is little water left to enter the soil.
• It is, however, most effective in promoting plant growth in temperate climates. The main reason for this is that it only happens in the mid-latitudes during the warm season, when the vegetation is very active.
C. Frontal Precipitation
It happens when deep and large air masses are forced to converge and move upward, allowing for adiabatic cooling. This type of precipitation necessitates air mass lifting. There are two ways to achieve cyclonic precipitation:
a. When two air masses with different temperatures and moisture content collide at an angle, the warm and moist air is forced to rise above the heavier cold air.
b. Some air is forced up when air masses from different directions converge in the center.
• Converging air masses in tropical regions have little difference in temperature and humidity. Convection is present as the lifting is almost vertical.
• Convergence provides the initial upward movement of the unstable air mass, resulting in large clouds and heavy showers.
• The front is a zone of contact between warm and cold air masses in temperate regions. It's possible that a warm or cold front will pass through. When warm, moist air rises slowly over a cold air mass, frontal precipitation occurs.
• The mixing of air along the front is the primary cause of this precipitation. Drizzle is the main form of frontal precipitation along the warm front. It is always present and lasts a long time. When a cold front comes through, it always comes in the form of intense thunder showers and lasts only a few hours.
• In Europe and North America, frontal precipitation occurs. In the northern parts of India, cyclonic precipitation occurs during the winter season.
Air-Masses And Temperate Cyclones
“An air mass may be defined as a large body of air whose physical properties, especially tem-perature, moisture content, and lapse rate, are more or less uniform horizontally for hundreds of kilometers”.
• An air mass is a large body of air that moves over the surface of the earth as a distinct entity with uniform physical properties at a given altitude. The global planetary wind system is made up entirely of air masses. As a result, they are linked to one or more wind belts.
• It should be noted that because a single air mass can cover hundreds of thousands to millions of square kilometers of the earth's surface, horizontal homogeneity of an air mass in terms of physical properties may not be practical, because the nature and degree of uniformity of air mass properties are determined by
1. The properties of the source area.
2. Changes in the air mass caused by its departure from the source area, and
3. The age of the air mass.
• Two basic properties of an air mass that control the weather conditions of the area affected by that air mass are the vertical distribution of temperature in the air mass and the moisture content of the air. When the temperature of an air mass is lower than the temperature of the underlying surface, it is called cold air mass; when the temperature is higher, it is called warm air mass.
• Continental air masses form over land, whereas maritime air masses form overseas. Tropical air masses form in the tropics, while those formed at higher latitudes are referred to as polar air masses.
• The front is the boundary between two opposing air masses. The physical properties of an air mass are determined by the physical characteristics of the surface it passes through.
• An air mass influences and modifies the temperature and moisture conditions of the areas it passes through, and it is in turn influenced by the local conditions of the areas it passes through.
There Are Six Major Source Regions of Air Masses On The Earth’s Surface
1) Oceanic polar regions (North Atlantic Ocean between Canada and Northern Europe, and North Pacific Ocean between Siberia and Canada-during winter season),
2) Polar and arctic continental areas (snow-covered areas of Eurasia and North America, as well as the Arctic region in the winter),
3) Tropical oceanic areas (anticyclonic areas – year-round);
4) Tropical continental areas (North Africa-Sahara, Asia, and the Mississippi Valley region of the United States – most developed in the summers),
5) Equatorial regions (zones between trade winds that are active all year) and
6) Monsoon lands of S.E. Asia.
Temperate Cyclones
• Temperate cyclones are active in both hemispheres over the mid-latitudinal region between 35° and 65° latitude. Extra-tropical, mid-latitude, and wave cyclones are other names for these cyclones.
• As a result, they're almost entirely found within the band of westerly winds. Their general movement is eastward, which explains why mid-latitude weather forecasting is essentially a west-facing profession.
• Because each mid-latitude cyclone or temperate cyclone differs in greater or lesser detail from the others, any description can only be general. The following discussions are about “typical” or idealized conditions.
• In the Northern Hemisphere, mid-latitude cyclones or temperate cyclones have a converging counterclockwise circulation pattern, while in the Southern Hemisphere, they have a clockwise circulation pattern. Cool air from the north meets warm air from the south in this wind flow pattern.
• The convergence of these opposing air masses typically produces two fronts:
1. a cold front that extends southwest from the storm's center and runs along the pressure trough extending from the storm's center, and
2. a warm front that extends eastward from the storm's center and runs along another, usually weaker, pressure trough. Frontogenesis (front formation), Occlusion (one front overriding the other), and Front lysis are the stages of temperate cyclone evolution.
• Dimensions and Form: - The temperate cyclones have an inverted V shape and are asymmetrical. They range in length from 500 to 600 kilometers. They could travel up to 2500 kilometers across North America. They range in height from 8 to 11 kilometers.
Structure: -
The cold sector is one where cold airmass reigns supreme, whereas the warm sector is dominated by warm airmass. Dark nimbus clouds and torrential downpours are common along the cold front, whereas rainfall along the warm front is mostly in the form of drizzle and is spread out over a longer period of time.