Collision

When two air masses with different temperatures and moisture content collide, they cause atmospheric disturbances. When the warm air rises, its cooling causes water vapor to condense and the formation of clouds and precipitation. A mass of warm and light air is always forced upward, while the colder and heavier air acts like a wedge. This cold-air wedge undercuts the warmer air mass and forces it to rise more rapidly. This effect can cause variable, sometimes stormy, weather. •

Cold Fronts

These fronts occur when cold air is moved by the wind and collides with warmer air. Warm air is driven upward. The water vapor contained in the air forms cumulus clouds, which are rising, dense white clouds. Cold fronts can cause the temperature to drop by 10° to 30° F (about 5°-15° C) and are characterized by violent and irregular winds. Their collision with the mass of ascending water vapor will generate rain, snow flurries, and snow. If the condensation is rapid, heavy downpours, snowstorms (during the cold months), and hail may result. In weather maps, the symbol for a cold front is a blue line of triangles indicating the direction of motion.

Very dense clouds that rise to a considerable altitude

Cold front

Warm front

STATIONARY FRONTS

These fronts occur when there is no forward motion of warm or cold air—that is, both masses of air are stationary. This type of condition can last many days and produces only altocumulus clouds. The temperature also remains stable, and there is no wind except for some flow of air parallel to the line of the front. There could be some light precipitation.

Cold air

Warm air

Cold front

Warm front

Behind the cold front, the sky clears and the temperature drops.

precipitation in the area with warm weather.

A long Rossby wave develops in the jet stream of the high troposphere.

the formation of a meander of warm and cold air can provide the conditions needed to generate cyclones.

Cold air

Warm air

Entire Continents

Fronts stretch over large geographic areas. In this case, a cold front causes storm perturbations in western Europe. But to the east, a warm front, extending over a wide area of Poland, brings light rain. These fronts can gain or lose force as they move over the Earth's surface depending on the global pressure system.

125 miles

A warm front can be 125 miles (200 km) long. A cold front usually covers about 60 miles (100 km). In both cases, the altitude is roughly 0.6 mile (1 km).

Surface warm front

Surface warm front

Warm Fronts

Cold front

Warm air

OCCLUDED FRONTS

When the cold air replaces the cool air at the surface, with a warm air mass above, a cold occlusion is formed. A warm occlusion occurs when the cool air rises above the cold air. These fronts are associated with rain or snow, cumulus clouds, slight temperature fluctuations, and light winds.

Thick rain clouds

Cold front

Warm air

Cool air

^^ These are formed by the action of winds. A mass of warm air occupies a place formerly occupied by a mass of cold air. The speed of the cold air mass, which is heavier, decreases at ground level by friction, through contact with the ground. The warm front ascends and slides above the cold mass. This typically causes precipitation at ground level. Light rain, snow, or sleet are typically produced, with relatively light winds. The first indications of warm fronts are cirrus clouds, some 600 miles (1,000 km) in front of the advancing low pressure center. Next, layers of stratified clouds, such as the cirrostratus, altostratus, and nimbostratus, are formed while the pressure is decreasing.

A barely noticeable imbalance of a warm front

Behind the cold front, the sky clears and the temperature drops.

Rossby Waves

Large horizontal atmospheric waves that are associated with the polar-front jet stream. They may appear as large undulations in the path of the jet stream. The dynamics of the climatic system are affected by these waves because they promote the exchange of energy between the low and high latitudes and can even cause cyclones to form.

precipitation in the area with warm weather.

A long Rossby wave develops in the jet stream of the high troposphere.

the Coriolis effect accentuates the wave action in the polar air current.

the formation of a meander of warm and cold air can provide the conditions needed to generate cyclones.

the Coriolis effect accentuates the wave action in the polar air current.

Thick rain clouds

A barely noticeable imbalance of a warm front

As the clouds extend over a region, they produce light rain or snow.

The mass of cold air takes the form of a retreating wedge, which has the effect of lifting the warm air as it moves over the mass of cold air.

As the clouds extend over a region, they produce light rain or snow.

The mass of cold air takes the form of a retreating wedge, which has the effect of lifting the warm air as it moves over the mass of cold air.

If the warm front moves faster than the retreating wedge of cold air, the height of the advancing warm front continues to increase.

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Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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