Winds of winter / solar winds 2020

Winds 

       We feel the wind but cannot see it. When certain objects in our surroundings move, we experience winds. The movement of air is called wind. Why does air move ? Winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The two main causes of large - scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect ). Within the tropics and subtropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations.   In coastal areas the sea breeze / land breeze cycle can define local winds, in areas that have variable terrain, mountain and valley breezes can prevail. Winds have various aspects : Velocity (wind speed); the density of the gas involved; energy content or wind energy. Th wind is also a critical means of transportation for seeds, insects, and birds, which can travel on wind currents for thousands of miles. In meteorology, winds are often referred to according to their strength, and the direction from which the wind is blowing. Short bursts of high speed wind wind are termed gusts. Strong winds of intermediate duration (around one minute) are termed squalls. Long - duration winds have various names associated with their average strength, such as breeze, gale, storm, and hurricane. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space.

          Wind powers the voyages of sailing ships across Earth's oceans. Hot air balloons use the wind to take short trips, and powered flight uses it to increase life and reduce fuel consumption. Areas of wind shear caused by various weather phenomena can lead to dangerous situations for aircraft. When winds become strong, trees and aircraft. When winds become strong, trees and human - made structures can be damaged or destroyed. Winds that are accelerated by rough topography and associated with dust outbreaks have been assigned regional name in various part of the world because of their significant effects on those regions. Wind also affects the spread of wildfires. Winds can disperse deeds from various plants, enabling he survival and dispersal of those plant species, as well as flying insect populations. When combined with cold temperatures, the wind has a negative impact on livestock.

Try This 

• Fold a paper into two same -sized rolls. 
• Keep both the paper rolls on one side of a table.
• You and your friend should select one roll each.
• Without touching the role of the paper or the table, what can be done to move the   paper rolls  to the other end of the table ?
•  See who moves the paper roll first to the other end of the table.
•  What could be the reason of the delay in making the rolls reach to the other end of the table ?
• What can we do to move the rolls to the other end of the table with a greater speed ?
• Can a bottle filled with water be moved to the other end of the table in this manner ? Can we  see  the same method that you tried for moving the paper rolls?

         Air moves from high pressure areas towards low pressure areas in a horizontal manner. Winds are generated due to this movement. The extent of the difference in the air pressure affects the velocity of the wind. If there is less difference in the pressure, winds blow with less velocity. Winds blow with  greater velocities if the pressure difference is greater. Wind speed also varies. Wind velocity is measured in the units of knots or kilometer's per hour.

       When we consider the earth as a whole, we find the direction of the winds is influenced by the rotation of the earth. In the northern hemisphere, winds get deflected towards the right of their original direction, whereas in the southern hemisphere they get deflected towards the left of their original direction. This direction has been shown by curved arrows in the figure. The rotation from west to east causes this change in the original direction of the winds. Winds are knows by the direction from which they blow. For example, Westerlies are winds that blow from the west. The direction of blowing, the duration, the regions covered, and the condition of the air determine the following wind types :

Planetary Winds : Some winds blow regularly on the earth from high to low pressure belts throughout the year. These winds cover a large portion of the earth, hence these are called planetary winds.

For example , the Easterlies, the Westerlies and the Polar winds.

         

       In both the hemispheres, the winds blow from the high pressure are between 25 and 35 parallels, to the equatorial low pressure belt. Due to the rotation of the earth, their original direction changes. In the northern, hemisphere, they blow from the north - east to the south - west whereas in the southern hemisphere  they blow from the south -east to the north -west. These winds coming from both the sides converge near the equatorial calm belt. These winds are knows as the Easterlies. In both the hemispheres, winds blow from the mid - latitudinal high pressure belt to the subpolar low pressure belt situated near 60 parallel. Their original direction changes due to the rotation of the earth. In the southern hemisphere, these winds blow from the north - west to the south - east  and in northern hemisphere, they blow from the south - west to the north - east. These winds are called Westerlies. In both the hemispheres, winds blowing from the polar high pressure belt to the subpolar low pressure belt (55 to 65) are called polar winds. Generally, they blow from east to west.

Do You Know ? Winds in the southern hemisphere blow with great velocities. The southern hemisphere is mostly occupied by oceans. In this hemisphere the obstacle caused by the relief of the land surface is almost absent. As there is no obstacle ; winds blow with greater velocities in the southern hemisphere  as compared to the northern hemisphere.

 Their characteristics are as follows:

Beyond 40 S, winds blow with tremendous velocities, These winds are called Roaring Forties . Around 50 S, winds are stormy. Hence they are called Furious Fifties. The stormy winds around 60 S make tremendous noise and hence they are called Screeching Sixties. Why are such winds not found in the northern hemisphere at 40, 50 and 60 parallels ?

Local Winds : The winds that blow for a short duration of time, originate in specific regions and blow over a limited area are called local winds. Local winds affect the climate of the region were they blow. These winds are known by different local names in  the different regions where they blow. Winds which blow in some restricted areas in different parts of the earth. These are known by different names.

Easterlies : Winds arriving from the east. These are the planetary winds blowing towards the equatorial low pressure belt from he mid-latitudinal high pressure belts in both he hemispheres.

Seasonal Winds: Winds which blow during specific period and in limited areas. For example, the monsoon winds. Seasonal winds are movements of air repetitively and predictably driven by changes in large - scale weather patterns. Seasonal winds occur in many locations throughout the world. The name assigned to a particular seasonal wind - and the underlying physical forces that drive the winds one of the most commonly recognized seasonal winds are the monsoon winds. Although monsoons are often erroneously identified as rainstorms, they are actually a seasonal wind. A monsoon is a wind in low - latitude climates that seasonally changes direction between winter and summer. Monsoons usually blow from the land in winter (called the dry phase, because the wind is composed of cool, dry air), and from water to the land in summer (called the wet phase, because the wind is composed of warm, moist air), causing a drastic change in the precipitation and temperature patterns of the area impacted by the monsoon.

Characteristics of the Mountain Breeze : 

•  Mountains cool down quickly at night. 
•  The valley zone is comparatively warmer.
•  Air pressure is greater on the mountains.
•  Winds blow from the mountain towards the valley.
•  The hot and light air from the valley is pushed upwards and the cool air rushes down into the valley.
• Mountain winds set in after sunset.

Westerlies : Winds arriving from the west. These are the planetary winds blowing from the mid - latitudinal high pressure belts towards the sub - polar low pressure belts in both the hemispheres. The westerlies are strongest in the winter hemisphere and times when the pressure is lower over the poles, while they are weakest in the summer hemisphere and when pressures are higher over the poles. The westerlies are particularly strong, especially in the Southern Hemisphere (called also 'Brave West winds' at striking Chile, Tasmania and New Zealand, in areas where land is absent, because land amplifies the flow pattern, making the current more north - south oriented, slowing the westerlies. Th descriptor "extratropical" refers to the fact that this type of cyclone generally occurs outside of the tropics, in the middle latitudes of the planet, where the Westerlies steer the system generally from west to east. These systems may also be described as mid - latitude cyclones" due to their area of formation, or "post - tropical cyclones" where extratropical transition has occurred, and are often described as "depressions " or "lows" by weather forecasters and the general public, These are the everyday phenomena which along with anticyclones, drive the weather over much of the Earth.

Do You Know ? The region up to 5 north and 5 south of the equator remains clam for most of the year and winds do not blow in this region. It is called the equatorial calm zone or Doldrums. In the area near the Tropic of Cancer and Tropic of Capricorn, that is, between 25 and 35 north and south, there exists a high pressure belt.  This is also a calm belt. This belt is known as Horse Latitudes.

           The land is made up of dense matter. Land is stable and opaque. As a result, heat is transferred at a greater speed and in a higher proportion. Hence, land gets heated quickly. The density of water is comparatively less. Water is transparent and unstable. Hence, water does not get heated quickly. As a result,  the air pressure in land and water areas is different. In the coast areas, land gets heated during daytime. Hence, the air on the land also gets heated and  the air pressure on land decreases. The sea water gets heated slowly hence the air is less heated and the air pressure remains high. Winds blowing from the sea  towards the land are called sea breezes. At night, land cools down faster as compared to he sea and therefore has higher air pressure. Hence, the land breeze blows from land towards the sea. 

 

       Besides these, winds blow under particular conditions in different areas. These are also called local winds. For example, Fohn, Chinook, Bora, Loo, etc.

Knots : A unit used to express the wind velocity. When the wind is lowing at a velocity of 1 Nautical mile (1.853 km) per hour, it is said to have velocity of one knot. (1 statute mile = 1.609 km). The word knot also indicates 1 minute are distance along equatorial circumference.

Major local winds in the world ::

Name of the Wind : Loo, Simoom, Chinook (Snow eater), Mistral, Bora, Pampero, Fohn (Faehn)

Nature of the Wind : 

Characteristics and areas of influence :

Seasonal winds (Monsoon) 

         Monsoon winds are generated due to the uneven heating of land water in the different seasons. During summers. Monsoons blow from the sea to the land in winter they blow from the land  to the sea. Southeast Asia. East Africa, North Australia are the regions where the Pronounced effects of these winds are felt . The influence of monsoon winds is seen in the summer and winter seasons in the Indian subcontinent. Due to these winds, the Indian subcontinent experiences monsoon (rainy) and retreating monsoon seasons apart from summer and winter.

Monsoon winds are in fact sea and land breezes blowing on large scale.

         Most of the precipitation in the Indian subcontinent is the effect of monsoon winds. After crossing the equator, they blow from the south - west towards the Indian subcontinent during the period from June to September. They are called the south - west monsoons. They are full of moisture. From September to December, because of the low pressure area developing near the equator, winds blow from the Indian subcontinent towards the equator. These are called the north - east monsoon winds. They are dry winds.

Cyclones : Cyclonic conditions are created when a low pressure area is surrounded by high pressure areas, In these conditions, winds start blowing towards the low pressure area from the surrounding high pressure areas. Due to the rotation of the earth. the cyclonic winds in the northern hemisphere move in an anticlockwise direction, whereas they move in a clockwise direction in the southern hemisphere. During a cyclone, the sky is cloudy, winds blow with a very high velocity and it rains heavily. The area affected by cyclones is limited. The duration, velocities direction and place of origin of these winds is unpredictable. A condition of lowering of air pressure in a region. Under such a condition, the air from the surrounding regions rushes to the central low pressure area in a circular manner. This leads to the formation of a system of whirling winds that moves from one place to other under the influence of prevailing regional winds. Cyclones can transition between extratropical, subtropical, and tropical phases. Mesocyclones form as warm core cyclones over land, and can lead to tornado formation. Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear. The growth of instability in the vortices is not universal. 

Cyclonic storms : Cyclones occurring in the western part of the Pacific Ocean along the coasts of Japan, china, Philippines, etc. are knows as Typhoons These storms arise in the months between June and October. Due to high velocity winds and heavy rains these prove to be destructive. The cyclones in the Caribbean Sea are knows as hurricanes. These are also destructive in nature. During these storms, the minimum velocity of the wind is 60 KM per hour. Cyclones also originate in the temperate zone but they are not so powerful and hence are not destructive. The cyclones in the Caribbean Sea are knows as hurricanes. These are also destructive in nature. During these storms. the minimum velocity of the wind is 60 KM  per hour. Cyclones also originate in the temperate zone but they are not so powerful and hence are not destructive. Air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere and clockwise as viewed from above (opposite to an anticyclone). Cyclones are characterized by inward - spiraling winds that rotate about a zone of low pressure. The largest low - pressure systems are polar vortices and extratropical cyclones of the largest largest scale (the synoptic scale). Warm - core cyclones such as tropical cyclones and subtropical Cyclones have also been seen on extraterrestrial planets, such as Mars, Jupiter, and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as wavs in large regions of enhanced mid - latitude temperature contrasts called baroclinic zones. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream. Strong cold fronts typically feature narrow bands of thunderstorms and severe weather, and may on occasion be preceded by squally lines or dry lines. Such fronts form west of the circulation center and generally move from west to east warm fronts form east of the cyclone center and are usually preceded by stratiform precipitation and fog.

Anticyclones : Under specific atmospheric conditions, the air pressure in a  particular region increases and the pressure in the surrounding areas remain low. In this situation, winds blow from the Centre toward the surrounding areas in a circular manner. In the northern hemisphere, these winds blow in a clockwise direction whereas in the southern hemisphere, they blow in an anticlockwise direction, During anticyclones, the skies are clear, winds blow with lesser velocities and the weather is pleasant. Anticyclones generally last for a few days or a week. Such anticyclones originate in temperate zones. At times, the air pressure in a region increase more than, the surrounding areas. Under such conditions, winds blow from the central high pressure areas towards the low pressure in the surrounding areas in a circular manner. Such winds moving out wards from the central. regions in a circular manner are called anticyclones. On weather maps, the Centre of an anticyclone is represented by the letter 'H' Anticyclones are vividly experienced in high pressure belts. Winds in these regions are always moving out and hence the rainfall in such areas is quite low.

Cyclones occurring in different parts of the world are assigned different names. A list of names is prepared for each of the oceans or its part. Names in the list are suggested by the countries in the region of that ocean. If the wind speed in the storm exceeds 33 knots (60 KM/ HOUR) the cyclone is assigned a name. Names make it easier for us to remember a particular storm.