Trade Winds

To understand trade wind it is important to understand what is wind. The wind is defined as the flow of gases or air on a large scale from the high-pressure area to low pressure area. Wind can be classified based on the following parameters:

  • Spatial scale (used for classifying large approximation)
  • Speed
  • Types of forces
  • Regions in which they occur

Based on the above parameters, wind can be classified into different types:

  • Planetary winds: These winds are also known as prevailing winds and are caused due to the difference in air pressure from one latitude to another latitude.
  • Trade winds: These winds are mainly caused due to the Coriolis effect and Ferrel’s law. They blow as north-eastern trades in Northern Hemisphere and as south-eastern trades in Southern Hemisphere.
  • The westerlies: These winds are developed between 40° and 65°S latitudes and these latitudes are known as the Roaring Forties, Furious Fifties and Shrieking Sixties.
  • Periodic winds: These winds are dependent on seasons and change their direction accordingly like monsoons.
  • Local winds: These are caused due to local differences in temperature and pressure and classified as hot, cold, conventional and slope.

What Are Trade Winds?

Trade winds can be defined as the wind that flows towards the equator from the north-east in the Northern Hemisphere or from the south-east in the Southern Hemisphere. These are also known as tropical easterlies and are known for their consistency in force and direction.

These winds are formed when the hot air rises and hits the equator where it is pulled towards the poles making them chilled. These winds are used by the sailors. Christopher Columbus discovered America with the help of trade winds.

Trade Winds

Below is the table of links explaining the other concepts:

What Are Westerlies?

The winds that blow from the west towards the east in the middle latitudes between 30° and 60° latitude in both northern and southern hemispheres. These winds get their name from their direction of origin. These are blown from the horse latitudes towards the poles. In the Northern Hemisphere, these are predominantly from the south-west and in the Southern Hemisphere, they are from the north-west. The weather patterns in the United States and Canada are due to westerlies.

What Are Easterlies?

The easterlies or polar easterlies are located between 60° and 90° latitude in both northern and southern hemispheres and are named after the direction they originate from. These are formed when the cool air from the poles sinks and moves towards the equator. The winds are curved towards the west by the Coriolis effect. These winds are important for sailors.

What is Coriolis Effect?

The Coriolis effect is defined as the inertial or fictitious force responsible for the deflection of winds towards the right in the Northern Hemisphere and towards the left in the Southern Hemisphere. Coriolis effect is used for deriving Ferrel’s law.

Following is the equation of motion for an object in an inertial reference:

F = ma


  • F is the vector sum of physical forces acting on the object
  • m is the mass of the object
  • a is the acceleration of the object relative to the inertial reference frame
  • The above equation can be turned into a non-inertial reference frame as:

    \(F-m\frac{d\Omega }{dt}*r-2m\Omega *{v}’-m\Omega *(\Omega *r)=m{a}'\)


  • ꭥ is the rotational vector
  • v’ is the velocity relative to the rotating reference frame
  • r is the position vector of the object
  • a’ is the acceleration relative to the rotating reference frame
  • Stay tuned with BYJU’S to learn more about other Physics related concepts with the help of interactive videos.

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