A weather front is the boundary that separates two air masses of different densities, and is a major cause of meteorological phenomena outside the tropics. In surface weather analysis, the front is illustrated using various triangles and semicircles colored, depending on the front type. The air mass separated by the front is usually different in temperature and humidity.
The cold front may show a narrow circle of lightning storms and bad weather, and can sometimes be preceded by striped stripes or dry lines. The warm front is usually preceded by stratiform deposits and fog. The weather is usually bright quickly after the front. Some fronts do not produce rainfall and are slightly cloudy, although there is always a shift in the wind.
Cold fronts and clogged fronts generally move from west to east, while warm fronts move toward the poleward. Due to greater air density behind them, cold fronts and cold occlusions move faster than warm fronts and warm occlusion. Mountains and warm bodies can slow down the movement of the front. When the front becomes stationary - and the density contrast on the frontal border is gone - the front can turn into a line separating the area with different wind speeds, known as shearlines. This is most common over the open ocean.
Video Weather front
Bergeron Classification of air masses
Bergeron classification is the most widely accepted form of air mass classification. Air mass classification is indicated by three letters. The first letter describes the nature of its humidity, with c being used for the air mass of the continent (dry) and m for the maritime air masses (moist). The second letter describes the thermal characteristics of the source region: T for tropical, P for pole, A for Arctic or Antarctic, M for monsoon, E for equator, and S for superior air (dry air formed by significant upward movement in the atmosphere). The third letter shows the stability of the atmosphere. If the air mass is colder than the ground beneath it, it is labeled k. If the air mass is warmer than the ground beneath it, it is labeled w. The air mass front is separated from different types or origins, and is located along a low-pressure valley.
Maps Weather front
Surface weather analysis
Surface weather analysis is a special type of weather map that provides weather element views over a geographical area at any given time based on information from weather stations on land. Weather maps created by plotting or tracking relevant quantity values ​​such as sea-level, temperature, and cloud cover to geographic maps to help find synoptic-scale features such as weather fronts. Surface weather analysis has a special symbol that shows the frontal system, cloud cover, precipitation, or other important information. For example, a H can represent high pressure, implying a sunny weather. An L on the other hand may represent low pressure, which often accompanies precipitation. Low pressure also creates a surface wind that comes from high pressure zones. Various symbols are used not only for frontal zones and other surface boundaries on weather maps, but also to describe the current weather in various locations on the weather map. In addition, the deposition area helps determine the frontal type and location.
Front Type
There are two different meanings used in meteorology to describe the weather around the frontal zone. The term "anafront" describes boundaries indicating instability, which means the air rises rapidly along and over the boundary causing significant weather changes. A "foreground" is weaker, bringing small changes in temperature and humidity, as well as limited rainfall.
Cold front
The cold front lies at the leading edge of the temperature drop, which in isotherm analysis appears as the leading edge of the isotherm gradient, and is usually located within a sharp surface trough. Cold fronts often carry thunderstorms, rain, and hail. The cold front can produce sharper weather changes and move two times faster than warm fronts, as cold air is denser than warmer air and quickly replaces the warm air that precedes the boundary. On the weather map, the position of the cold front surface is marked with a triangle-shaped pips blue line symbol that points toward the journey, and is placed at the leading edge of the cold air mass. Cold fronts come in connection with low pressure areas. The colder concept, the "winding" dense air under denser and denser air is often used to describe how air is lifted along the frontal boundary. The cold air pinched under the warmer air creates the strongest wind just above the ground, a phenomenon often associated with wind blows that destroy property. This appointment will then form a row of rain and a narrow storm if there is enough moisture. However, this concept is not an accurate description of the physical process; upward motion is not produced because the warm air "increases" the cold and solid air, on the contrary, the frontogenetic circulation is behind the forcing upward.
Warm front
The warm front is at the leading edge of a homogeneous warm air mass, located on the edge of the equatorial gradient in the isotherm, and located in a wider lower pressure trough than the cold front. The warm front moves slower than the cold front that usually follows because the cold air is denser and harder to remove from the Earth's surface.
It also forces temperature differences across warm fronts for a wider scale. The clouds in front of the warm front are mostly stratiform, and rainfall gradually increases as the front closes. Fog can also occur before the warm front. Clearing and heating is usually quick after the frontal part. If the warm air mass is unstable, a lightning storm can be embedded between stratiform clouds in front of the front, and after the frontal line, the scatter may continue. On the weather map, the location of the warm front surface is indicated by a semi-circular red line that leads to the journey.
Hidden front
The clogged front is formed when the cold front passes over the warm front, and usually forms around the low-pressure area of ​​mature. The cold and warm lines are naturally polar to the point of occlusion, also known as the triple point. It lies inside a sharp trough, but the mass of air behind the border can be warm or cold. In cold occlusion, the air masses overtake the warmer fronts colder than the cold air in front of the warm front and plow under both air masses. In warm occlusion, the air masses overtake the warm front warmer than cold air in front of the warm front and riding over the mass of cold air while lifting warm air.
Various kinds of weather can be found along the clogged front, with the possibility of lightning storms, but usually their parts are related to air drying masses. In the front occlusion, the air circulation brings warm air up and sends the draft cool air down, or vice versa depending on the front occlusion experienced. Precipitates and clouds are associated with trowal , the projection on the Earth's surface of a high warm air tongue formed during the process of depression occlusion.
The hidden front is indicated on a weather map with a purple line with a semicircle and alternating triangles pointing towards the journey. Trowal is represented by a series of blue and red connection lines.
Stationary front
A stationary front is an immovable (or stuck) boundary between two air masses, both of which are not strong enough to replace the other. They tend to remain essentially in the same area for a long time, usually moving in waves. There is usually a large temperature gradient behind the boundary with larger isotherm packaging.
Various kinds of weather can be found along the stationary front, but usually prolonged clouds and precipitation are found there. Stationary fronts either disappear after a few days or move to a sliding line, but they can turn into cool or warm fronts if conditions change greatly. The stationary front is marked on a weather map with alternating half red circles and blue spikes pointing in the opposite direction, indicating no significant movement.
When the stationary front becomes smaller on a scale, it degenerates into a narrow zone where the wind direction changes significantly over a relatively short distance, they become known as shearlines. A shearline is described as a dotted line and a red line. The stationary front can carry snow or rain for long periods of time.
Dry path
A similar phenomenon to the future weather is a dry line, which is the boundary between air masses with significant moisture differences. As the human group rises on the north side of the surface altitude, the lowered pressure area will form the direction of wind from the north-south oriented mountain chain, leading to the formation of the ship's trough. Near the surface during the daytime, warmer moist air is denser than dry air with greater temperature, and thus warm wet air wedges under drier air like a cold front. At higher altitudes, warmer moist air is less dense than dry air and the upside-down slope. Around the high reversal, bad weather may occur, especially when the triple point is formed with a cold front. The weaker shapes of the more commonly seen dry lines are the lowest troughs, indicating weaker moisture differences. When moisture swims along the boundary during the warm season, it can be the focus of diurnal lightning storms.
Dry lines can occur anywhere on earth in the area between the desert and warmer seas. The southern plain west of the Mississippi River in the United States is a well-liked location. Dry lines usually move eastward during the day and westward at night. The dry line is depicted on the National Weather surface analysis (NWS) as an orange line with a scallop facing the humid sector. The dry line is one of the few surfaces in which the indicated pips do not reflect the direction of movement.
Squall line
The organized area of ​​thunderstorm activity not only reinforces pre-existing front zones, but can run faster than cold fronts in a pattern where the upper jet splits into two streams, with the resulting Mesoscale Convective System (MCS) formed at the top level split in a wind pattern that flows southeast into the heat sector parallel to the low-level line of thickness. When convection is strong and linear or curved, the MCS is called a squall line, with features placed at the leading edge of a wind shift and a significant rise in pressure. Even weaker and less organized storm areas lead to cooler air and higher pressure, and the outflow limit is ahead of this type of activity, which can act as a focus for additional lightning storm activity later on.
These features are often depicted in warm seasons across the United States on surface analysis and are located inside surface troughs. If the outflow limit or squall line is formed over a dry area, haboob may occur. The squall lines are depicted on NWS surface analysis as an alternating pattern of two red dots and broken lines labeled SQLN or SQUALL LINE, while the outbound boundaries are described as troughs with the LIMITATION label.
Precipitation generates
The front is the main cause of significant weather. Convective rainfall (heavy rainfall, snowstorms and associated unstable weather) is caused by air lifted and condensed into cloud by the movement of the front cold or cold occlusion under warmer and moist air masses. If the temperature difference of the two large air masses is involved and the extreme turbulence due to wind shear and the presence of a strong jet stream, "rolls of cloud" and tornado may occur.
In warm seasons, wind cover, breeze, outflow and occlusion bounds can cause convection if enough moisture is available. Orographic rainfall is the rainfall created by the action of moving the moving air above the plains such as mountains and hills, the most common behind cold fronts that move into the mountains. Sometimes this happens before the warm front moves north to the east of the mountainous terrain. However, rainfall along the warm front is relatively stable, such as rain or drizzle. Fog, sometimes widespread and dense, often occurs in pre-warm-front areas. Although, not all fronts produce rain or even clouds because the humidity must be present in the air mass that is being lifted.
Movement
The front is generally guided by the wind above, but does not move quickly. The cold front and the clogged front of the Northern Hemisphere usually move from northwest to southeast, while warm fronts move more with time. In the northern hemisphere, a warm front moves from southwest to northeast. In the southern hemisphere, the opposite is true; the cold front usually moves from southwest to northeast, and the warm front moves from northwest to southeast. Movement is largely due to the gradient pressure force (horizontal difference in atmospheric pressure) and the Coriolis effect, caused by the spin of Earth about its axis. The frontal zone can be slowed down by geographical features such as mountains and large bodies of warm water.
See also
- Cyclophenesis
- Extratropical cyclones
- Norwegian cyclone model
- Surface weather analysis
- Trench (meteorology)
References
Bibliography
- (1999). Water Apparent: How Meteorologists Learn to Map, Predict and Dramatize the Weather . University of Chicago Press, Chicago.
External links
- Surface Analysis Manual
- Cold Front
- Warm Home
- The front: the boundary between air masses
Source of the article : Wikipedia
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