The Important Factors which Affect the Wind

The important factors which affect the wind are an important topic in general geography. Questions are frequently coming from this topic in competitive exams and aspirants need to make a strong hold on this topic. In this article, we are going to discuss the factors affecting the wind system and how it impacts the whole atmosphere.

Role of Winds :

• Wind refers to the horizontal movement of air.
  
• Current is the vertical air movement.
  
• Wind globally compensates for uneven pressure distribution.
  
• Wind helps move things like heat and moisture from one place to another.
  
• The sun is the ultimate force that drives the wind. The pressure difference causes the wind to flow from high pressure to low pressure. Pressure differentials are caused by uneven heating of the Earth’s surface by solar radiation.
  
• Surface wind is subject to friction. The rotation of the earth also affects the movement of the wind. The force exerted by the Earth’s rotation is known as the Coriolis force. Horizontal winds near the surface, therefore, respond to the combined action of three forces: the pressure gradient force, the frictional force, and the Coriolis force.
  
• Also, gravity acts downwards. Centripetal acceleration creates a circular flow pattern around the center of high and low pressure.

Factors Affecting the Wind

1. Pressure gradient force:

• Differences in atmospheric pressure create pressure gradient forces.
  
• The rate of change in air pressure over distance is the pressure gradient.
  
• Pressure gradient forces act from high pressure to low pressure, causing wind movement.
  
• The pressure gradient is stronger where the isobars are closer and weaker where the isobars are farther apart.
  
• The narrower slopes also indicate stronger wind speeds, as the mean steeper pressure changes. Wind direction follows the direction of pressure change. 
  

2. Coriolis force :

• The rotation of the Earth around its axis affects the direction of the wind. This force is also known as the Coriolis force. It has a great effect on the wind direction.
  
• Because of the Earth’s rotation, the wind does not cross isobars at right angles as determined by the pressure gradient force but is diverted from its original path. This misalignment is a result of the Earth’s rotation and is called the Coriolis effect or Coriolis force.
  
• This effect causes the wind to deflect to the right of its path in the northern hemisphere and the left in the southern hemisphere, according to Farrell’s law (winds deflect to the right in the northern hemisphere and to the left in the southern hemisphere). The southern hemisphere derived from the application of the Coriolis effect to air masses.
  
• This deflection force appears to exist only when the air begins to move and increases with increasing wind speed, air mass, and latitude.
  
• The Coriolis force acts perpendicular to the pressure gradient force (the pressure gradient force is perpendicular to the isobar).
  
• As a result of these two mutually perpendicular forces, winds blow in the low-pressure areas around them (cyclonic conditions).

3. Frictional force :

• The unevenness of the earth’s surface resists wind movement in the form of friction, which affects wind speed. 
  
• It is the largest on the surface of the earth and its influence generally extends to altitudes of 1 to 3 km. At sea level, friction is minimal.
  
• However, in rough terrain, the friction is so great that the wind direction makes a large angle with the isobars and the speed slows down. 
  

4. Centripetal force :

• It only works on air flowing around the center of circulation.
  
• Centripetal acceleration creates a force that is perpendicular to wind motion and directed inward toward the center of rotation (such as the center of low and high pressure). 
  
• This force creates a circular flow pattern around a center of high and low pressure.
  
• Centripetal acceleration is more significant in smaller circulations than in mid-latitude cyclones.
  

5. Atmospheric pressure :

• Wind speed and direction are the net results of the forces that create the wind. Upper atmospheric winds, 2-3 km above the surface, are not affected by surface friction and are controlled by pressure gradients and the Coriolis force.
  
• If the isobar is straight and frictionless, the pressure gradient force balances the Coriolis force and the resulting wind blows parallel to the isobar.
  
• The movement of the wind in the vicinity of the cyclone is called cyclonic circulation. In the vicinity of high pressure, it is called anticyclonic circulation. The direction of the wind around such a system varies with different hemispheric positions.
  
• Wind movement or wind circulation at the Earth’s surface in cyclones and anticyclones is often closely related to wind circulation at higher levels. In general, air over low-pressure areas converges and rises. In areas of high pressure, air sag from above and diverges at the surface.
  
• Apart from convergence, some eddies, convection, topographic uplift, and uplift along fronts lift the air. It is essential for the formation of clouds and precipitation.
  

More about the Coriolis effect

• The Coriolis effect is the apparent deflection of objects (airplanes, wind, missiles, sniper bullets, ocean currents, etc.) moving in a straight path concerning the Earth’s surface.
  
• It is also important to consider the “apparent” part of the definition of the Coriolis effect.
  
• This means that an airborne object (such as an airplane) can see the Earth slowly spinning beneath it. From the Earth’s surface, the same object appears out of orbit. The object has not deviated from its course, but this appears to be happening only because the Earth’s surface rotates underneath the object.

Causes of the Coriolis effect

• The prominent cause of the Coriolis effect is the rotation of the Earth. Because the Earth rotates counterclockwise around its axis, anything that flies or flows far away from the surface appears to be deflected.
  
• This happens because something is moving freely over the surface and the Earth below is moving east at a faster rate.
  
• The higher the latitude and the slower the Earth’s rotation speed, the greater the Coriolis effect.
  
• The plane itself flying along the equator can continue to fly over the equator without any distractions. A little north or south of the equator the plane will be deflected.
  
• The faster the object itself moves, the greater the deflection, in addition to the rotation speed and latitude of the Earth.