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1. What is air pressure?
Particles in the air exert a force against surfaces when large numbers of particles press against a surface,the overall effect is known as air pressure.
2. What is millibar?
Millibar is the unit of pressure used by meteorologists in drawing weather charts. One bar is divided into 1000 millibars.Millibars are known as hectopascals. One atmospheric pressure is equal to 1013 millibars.
3. What are the factors of pressure change?
There are two factors, which are responsible for the formation of high and low pressure.They are:
4. What is thermal factor?
Heating causes expansion,expansion results in decreasing the density and this leads to low - pressure.On the other hand,cooling results in contraction.This increases the density resulting in high pressure.
5. What is dynamic factor?
Along the equator,the velocity of the rotation of the Earth is very high,hence the centrifugal force is very strong.It throws the air mass out resulting in low pressure in the area.
6. What is mercurial barometer?
Mercurial barometer is an instrument used for measuring the change in the atmospheric pressure.It uses a long glass tube,open at one end and closed at the other. Air pressure is measured by observing the height of the column of mercury in the tube.At sea level,air pressure will push on the mercury at the open end and support a column of mercury about 30 inches high.
7. What is barographs?
The pressure in meteorological laboratories is measured on barographs. Barographs are self registering instruments that measure atmospheric pressure.
8. What are the main pressure belts ?
The pattern of pressure distribution generally corresponds with the heat zones or the temperature belts on the surface of the Earth.The main pressure belts found on the surface of the Earth are :
9. What is equatorial low pressure belt ?
Along the equator, within 15o north and south of it,15o the equatorial low pressure belt.The region around the equator is generally the hottest.Therefore,the air in this region heats up,expands and becomes lighter.There is total absence of surface winds causing a low pressure belt.This belt is also called the doldrums or the region of calm conditions.
10. What are sub-tropical high pressure belts ?
Sub-tropical high pressure belts are subtropical latitudes between 30 and 35 degrees both north and south,characterized by light winds and hot, dry weather.The belt in the Northern hemisphere is sometimes called the "calms of cancer" and the Southern hemisphere it is called the "calms of capricorn".
11. What is sub-polar low pressure belts ?
A belt of low pressure located,in the mean, between 50 and 70 degrees latitude; in the Northern hemisphere.This belt consists of the Aleutian low and the Icelandic low ; in the Southern hemisphere.It is supposed to exist around the periphery of the Antarctic continent .
12. What are polar high pressure belts ?
Around the north and the south poles,the air is so cold and heavy that it is unable to leave the surface.This weight of the cold air creates a high pressure belt over the poles.These high pressure belts are called polar high pressure belts.
13. What are the effects of pressure?
The following are the effects of pressure :
14. What is wind?
Wind is a horizontal movement of air caused by the uneven heating of the Earth by the Sun.It is the flow of air along, or parallel to,Earth's surface.Winds help to transfer energy in the atmosphere by mixing warm tropical air with cold polar air.It also help to moderate temperature on our planet.
15. What is wind vane ?
The direction of the wind is observed with the help of an instrument called the wind vane.It is used to see the direction of the wind.It is commonly known as the weather cock,because it is often made in that shape.It rotates very easily and the arrow points to the direction of the wind.
16. What is deflection ?
If the Earth did not rotate on its axis, all winds would blow straight from high pressure towards low pressure areas and die down when the pressure is equalized.But the Earth rotates,which is why winds curve when they blow.This curving of winds is called deflection and its motion is known as coriolis effect.
17. What is anemometer?
Wind speed is measured by an instrument called the anemometer.This instrument consists of four metal or plastic cups one arms that spin around a vertical pole and catches the wind,causing the assembly to rotate.The speed at which it rotates is usually transferred to an indicator on a calibrated dial.
18. What is barometer?
Atmospheric pressure is measured by instruments called barometer. Barometers use mercury to record change in pressure.
19. What is atmospheric pressure?
Atmospheric pressure is the pressure at any point on the surface of the Earth due to the weight of the column of air about that point. Air is made up of gases, which weighs and exerts a pressure on the Earth's surface called the atmospheric pressure.
20. What are the types of wind?
There are three types of winds.They are :
21. What are planetary winds?
Planetary winds are also known as primary winds.Local winds are caused by local changes in temperature.Similar air movements can occur on a worldwide scale due to worldwide variations in temperature.These vast movements are called planetary winds.
22. What are the types of planetary winds ?
There are three types of planetary winds.They are :
23. What are trade winds?
Trade winds are the prevailing winds that blow from subtropical high pressure to equatorial low pressure towards the equator from the north east and the south east. Trade winds are caused by hot air rising at the equator and the consequent movement of air from the north and the south to take its place.
