what are fronts and what causes them?
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changes in air pressure, and temperature at changing locations
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Wind: Creates dunes and erodes rock\nRain: Erode the land and forms the river and lakes\nGlaciers: Formation of the glaciers is due to atmospheric effects, so is their melting, which as they slide down mountains craves things up.
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Tornadoes are formed by the clashing of drasticlaly different masses of air known as fronts.  A high pressure front meets with a low pressure front and the difference in their temperatures and pressures creates a strong wind that can form into the funnel clouds known as tornadoes.  This is not to say that all colliding fronts will yield tornadoes, but there are certain elements that can increase the likeliness of a tornado forming.  The swath of the mid-west United States from N. Texas / Oklahoma through Kansas / Nebraska and into Iowa / Missouri is known as "Tornado Alley" because there are more tornados per year in this area than anywhere else in the world.
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That would be called a cold front.\n\nA front in general is when an air mass of uniform temperature & moisture content moves into an area w/ air of different properties already in place.\n\nCold fronts are denoted w/ a blue line & triangles pointing into the direction in which the front is traveling.\n\nOnce the cold front moves in, it brings with it much colder temperatures. So the colder temperatures are said to be behind the front.
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fluids - convection is due to the movement of molecules
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A\n\nVolcanic explosions such as St. Helen's are cause by super heat gases.  Often Steam.
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High and low pressure regions result from uneven heating of the surface and the movement of air masses.\n\nAreas of low pressure occur where air is being displaced upwards either due to convection or the movement of a front (usually a cold front). This usually results in unstable air, clouds, and rain. Wind circulates counter-clockwise around low-pressure centers in the northern hemisphere. \n\nAreas of high pressure occur where air is sinking - if you are in a high pressure zone where the air column is stable you experience clear skies.\n\nAlso there are regions around the United states that experience persistent highs or persistent lows - places where these pressure conditions are almost always present.
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volcanos\ntectonic plates movements
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This is what causes a surface current. \nAs winds blow across the ocean, there is friction between the wind and the water. Some of the energy of the wind is transferred to the water to make waves which travel across the surface of the ocean and some of the energy is transferred into surface currents.\nWhen currents run into something, like a continent, they must change direction. The current must turn right or left to form boundary currents or flow below the surface of the ocean to form a subsurface current.
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it's an area of high magnetic activity that keeps heat convection from occuring. Basically the magnetic forces cools the spot, making it darker in comparison to the rest of the surface of the sun. Sun spots also occurs in cycles of around 30 years, but nobody knows what causes is this...
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actual motion of heated matter in streams called convection currents.
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Cold and Warm air fronts crashing into eachother and making them both spiral downward.
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What causes tornadoes?\n\nThunderstorms develop in warm, moist air in advance of eastward-moving cold fronts. These thunderstorms often produce large hail, strong winds, and tornadoes. Tornadoes in the winter and early spring are often associated with strong, frontal systems that form in the Central States and move east. Occasionally, large outbreaks of tornadoes occur with this type of weather pattern. Several states may be affected by numerous severe thunderstorms and tornadoes.\n \nDuring the spring in the Central Plains, thunderstorms frequently develop along a "dryline," which separates very warm, moist air to the east from hot, dry air to the west. Tornado-producing thunderstorms may form as the dryline moves east during the afternoon hours. \nAlong the front range of the Rocky Mountains, in the Texas panhandle, and in the southern High Plains, thunderstorms frequently form as air near the ground flows "upslope" toward higher terrain. If other favorable conditions exist, these thunderstorms can produce tornadoes.\n\nTornadoes occasionally accompany tropical storms and hurricanes that move over land. Tornadoes are most common to the right and ahead of the path of the storm center as it comes onshore.
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All weather is brought about by thermal conditions. Cold as used in the term "cold front" is only a relative term. There is still quite a bit of "heat" in cold air. You must remember all measurements referencing thermal conditions are really a reference to absolute zero where there is no thermal activity.
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Wind is the roughly horizontal movement of air (as opposed to an air current) caused by uneven heating of the Earth's surface. It occurs at all scales, from local breezes generated by heating of land surfaces and lasting tens of minutes to global winds resulting from solar heating of the Earth. The two major influences on the atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect).\n\nGiven a difference in barometric pressure between two air masses, a wind will arise between the two which tends to flow from the area of high pressure to the area of low pressure until the two air masses are at the same pressure, although these flows will be modified by the Coriolis effect in the extratropics.\n\nWinds can be classified either by their scale, the kinds of forces which cause them (according to the atmospheric equations of motion), or the geographic regions in which they exist. There are global winds, such as the wind belts which exist between the atmospheric circulation cells. There are upper-level winds, such as the jet streams. There are synoptic-scale winds that result from pressure differences in surface air masses in the middle latitudes, and there are winds that come about as a consequence of geographic features such as the sea breeze. Mesoscale winds are those which act on a local scale, such as gust fronts. At the smallest scale are the microscale winds which blow on a scale of only tens to hundreds of metres and are essentially unpredictable, such as dust devils and microbursts.\n\nYou could get more information from the link below...
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Very briefly, the combined effects of the sun and earth's rotation provide the energy that drives storms. Solar heating heats the earth's surface, most strongly in tropic regions, and drives a water transport cycle by evaporating water from oceans, lakes etc. into the air. Convection conveys hot, moisture-laden tropical air toward the poles and cold polar air back toward the tropics. And the rotation of the earth causes these air movements to acquire a rotational component (Coriolis force). When cold air masses meet hot, moist air masses, the cold air may rise up over the hot air, or cold air may pass over hot, wet land, either scenario creating an instability. The overturning of this creates convective vertical air movements which may be augmented by the rotation. Downdraft convection is felt as winds on the ground. Within the storm cell, the hot moist air transfers heat to the cold air through water condensation, and this can bring rain or frozen precipitation. Updrafts of warm moist air form precipitation as the air is cooled due to reduced pressure at high altitude. Adjacent updrafts and downdrafts produce a type of wind shear that can cause aircraft to lose lift and crash.
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Warm fronts (lows, low pressure) ride over the top of cold fonts (highs, high pressure).  The winds are going in different directions and can spawn tornadoes.  Also, the water vapor in the warm front air cools as it gains altitude and produces rain.  If there is a lot of turbulence, the water can freeze into droplets of ice which keep going up and down and around in the turbulence produced by the interaction of these air masses.  This produces hailstones.\n\nWarm air is light and laden with water vapor.\nCold air is dryer usually, and always heavier than warm air.\n\nSo you got some different kinds of weather there.\n\nHuge masses of warm, water laden air are found in hurricanes.  The water is in huge, towering masses of clouds.\n\nIn the northern hemisphere, warm air masses (lows) spin counterclockwise.  Cold air masses (highs) spin clockwise.\n\nWarm air comes mostly from the south, cold air from the north.  However, air masses are steered by the Jet Stream also.  Maybe your next topic.\n\nHurricanes have the lowest pressure of all (low barometer reading).