StormStormStorm is any disturbed state of an astronomical body's

atmosphere, especially affecting its surface, and strongly implying severe weather. It may be marked by strong wind, thunder and lightning (a thunderstorm), heavy

precipitation, such as ice (ice storm), or wind transporting some substance through the atmosphere.

Formation Of StormFormation Of Storm Storms are created when a center of Storms are created when a center of low pressurelow pressure develops, develops,

with a system of with a system of high pressurehigh pressure surrounding it. This surrounding it. This combination of opposing forces can create winds and result combination of opposing forces can create winds and result in the formation of storm in the formation of storm cloudsclouds, such as the , such as the cumulonimbuscumulonimbus. Small, localized areas of low pressure can form from hot . Small, localized areas of low pressure can form from hot air rising off hot ground, resulting in smaller disturbances air rising off hot ground, resulting in smaller disturbances such as such as dust devilsdust devils and and whirlwindswhirlwinds. .

TypesTypes --Ice StormIce Storm --BlizzardBlizzard --SnowstormSnowstorm - Ocean Storm- Ocean Storm - - Super stormSuper storm --Dust devilDust devil - - SquallSquall -Gale -Gale --ThunderstormThunderstorm -Tropical Cyclone-Tropical Cyclone --HailstormHailstorm --TornadoTornado etc. etc.

MonsoonMonsoon

Monsoon is a seasonal prevailing Monsoon is a seasonal prevailing windwind that lasts for several that lasts for several months. The term was first used in English in months. The term was first used in English in IndiaIndia, , BangladeshBangladesh, , PakistanPakistan, and neighboring countries to refer , and neighboring countries to refer to the big seasonal winds blowing from the to the big seasonal winds blowing from the Indian OceanIndian Ocean and and Arabian SeaArabian Sea in the southwest bringing heavy in the southwest bringing heavy rainfallrainfall to the region. In to the region. In hydrologyhydrology, monsoon rainfall is , monsoon rainfall is considered to be that which occurs in any region that considered to be that which occurs in any region that receives the majority of its rain during a particular receives the majority of its rain during a particular season. This allows other regions of the world such as season. This allows other regions of the world such as North AmericaNorth America, , South AmericaSouth America, , Sub-Saharan AfricaSub-Saharan Africa, , AustraliaAustralia and and East AsiaEast Asia to qualify as monsoon regions. In to qualify as monsoon regions. In terms of total terms of total precipitationprecipitation and total area covered, the and total area covered, the monsoons affecting the Indian subcontinent dwarf the monsoons affecting the Indian subcontinent dwarf the North American monsoon. The South Asian monsoon North American monsoon. The South Asian monsoon affects a larger number of people due to the high density affects a larger number of people due to the high density of population in this part of the world.of population in this part of the world.

ProcessProcess Monsoons are caused by the larger amplitude of the seasonal Monsoons are caused by the larger amplitude of the seasonal cycle of land temperature compared to that of nearby oceans. This cycle of land temperature compared to that of nearby oceans. This differential warming happens because heat in the ocean is mixed differential warming happens because heat in the ocean is mixed vertically through a "mixed layer" that may be fifty meters deep, vertically through a "mixed layer" that may be fifty meters deep, through the action of wind and buoyancy-generated through the action of wind and buoyancy-generated turbulenceturbulence, , whereas the land surface conducts heat slowly, with the seasonal whereas the land surface conducts heat slowly, with the seasonal signal penetrating perhaps a meter or so. Additionally, the signal penetrating perhaps a meter or so. Additionally, the specific heat capacityspecific heat capacity of liquid water is significantly higher than that of liquid water is significantly higher than that of most materials that make up land. Together, these factors mean of most materials that make up land. Together, these factors mean that the heat capacity of the layer participating in the seasonal cycle that the heat capacity of the layer participating in the seasonal cycle is much larger over the oceans than over land, with the consequence is much larger over the oceans than over land, with the consequence that the air over the land warms faster and reaches a higher that the air over the land warms faster and reaches a higher temperature than the air over the ocean. The hot air over the land temperature than the air over the ocean. The hot air over the land tends to rise, creating an area of tends to rise, creating an area of low pressurelow pressure. This creates a steady . This creates a steady wind blowing toward the land, bringing the moist near-surface air wind blowing toward the land, bringing the moist near-surface air over the oceans with it. Similar rainfall is caused by the moist ocean over the oceans with it. Similar rainfall is caused by the moist ocean air being lifted upwards by mountains, surface heating, convergence air being lifted upwards by mountains, surface heating, convergence at the surface, divergence aloft, or from storm-produced outflows at at the surface, divergence aloft, or from storm-produced outflows at the surface. However the lifting occurs, the air cools due expansion in the surface. However the lifting occurs, the air cools due expansion in lower pressure, which in turn produces lower pressure, which in turn produces condensationcondensation. .

Intertropical Convergence ZoneIntertropical Convergence Zone

The Intertropical Convergence Zone (ITCZ), also known The Intertropical Convergence Zone (ITCZ), also known as the Intertropical Front, as the Intertropical Front, Monsoon troughMonsoon trough, or the , or the Equatorial Convergence Zone, is a belt of Equatorial Convergence Zone, is a belt of low pressurelow pressure girdling girdling EarthEarth at the at the equatorequator. It is formed by the . It is formed by the vertical ascent of warm, moist air from the latitudes vertical ascent of warm, moist air from the latitudes north and south of the equator.north and south of the equator.

The air is drawn into the intertropical convergence zone The air is drawn into the intertropical convergence zone by the action of the by the action of the Hadley cellHadley cell, a , a macroscalemacroscale atmosphericatmospheric feature which is part of the Earth's heat feature which is part of the Earth's heat and moisture distribution system. It is transported and moisture distribution system. It is transported aloft by the aloft by the convectiveconvective activity of activity of thunderstormsthunderstorms; ; regions in the intertropical convergence zone receive regions in the intertropical convergence zone receive precipitationprecipitation over 200 days in a year. over 200 days in a year.

PositionPosition The location of the intertropical convergence The location of the intertropical convergence

zone varies over time. Over land, it moves back zone varies over time. Over land, it moves back and forth across the equator following the sun's and forth across the equator following the sun's zenithzenith point. Over the oceans, where the point. Over the oceans, where the convergence zone is better defined, the seasonal convergence zone is better defined, the seasonal cycle is more subtle, as the convection is cycle is more subtle, as the convection is constrained by the distribution of ocean constrained by the distribution of ocean temperatures.temperatures.

Sometimes, a double ITCZ forms, with one Sometimes, a double ITCZ forms, with one located north and another south of the equator. located north and another south of the equator. When this occurs, a narrow ridge of high pressure When this occurs, a narrow ridge of high pressure forms between the two convergence zones, one forms between the two convergence zones, one of which is usually stronger than the other.of which is usually stronger than the other.

Tropical Waves or Easterly WavesTropical Waves or Easterly Waves

Tropical waves, or easterly waves, also known as African Tropical waves, or easterly waves, also known as African easterly waves in the easterly waves in the AtlanticAtlantic region, are a type of region, are a type of atmosphericatmospheric troughtrough, an elongated area of relatively , an elongated area of relatively low air pressurelow air pressure, oriented , oriented northnorth to to southsouth, which move from , which move from easteast to to westwest across the across the tropicstropics causing areas of causing areas of cloudinesscloudiness and and thunderstormsthunderstorms. West-moving waves can also form from . West-moving waves can also form from the tail end of the tail end of frontalfrontal zones in the zones in the subtropicssubtropics and tropics and and tropics and may be referred to as easterly waves, but these waves are may be referred to as easterly waves, but these waves are not properly called tropical waves; they are a form of not properly called tropical waves; they are a form of inverted troughinverted trough sharing many characteristics with fully sharing many characteristics with fully tropical waves. All tropical waves form in the easterly flow tropical waves. All tropical waves form in the easterly flow along the southern side of the along the southern side of the subtropical ridgesubtropical ridge or belt of or belt of high pressurehigh pressure which lies north and south of the Intertropical which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and formation of tropical cyclones in the north Atlantic and northeast Pacific basins.northeast Pacific basins.

CharacteristicsCharacteristics

A tropical wave normally follows an area of A tropical wave normally follows an area of sinking, intensely dry air, blowing sinking, intensely dry air, blowing northeast. After passing the trough line, northeast. After passing the trough line, the wind veers southeast, the humidity the wind veers southeast, the humidity abruptly rises, and the atmosphere abruptly rises, and the atmosphere destabilizes. This yields widespread destabilizes. This yields widespread showers and thunderstorms, sometimes showers and thunderstorms, sometimes severe. As the wave moves westward, the severe. As the wave moves westward, the showers gradually diminish.showers gradually diminish.