Types of Wind – Planetary, Periodic, Monsoon and Variable

Introduction

Moving air is called wind. The movent of air results due to the differences in pressure in the atmosphere. This difference in pressure results from the earth’s rotation and the sun’s heating effect. The greater the difference, the faster the movement and the stronger the wind. Based on the periodicity and location of occurrence, the wind is classified into four major types: Primary or Planetary winds, Secondary or periodic winds, and Tertiary or local winds. Let us discuss these winds more.

Planetary Winds

Primary winds are also known as planetary winds. These winds exist on earth throughout the year and blow in a particular direction. These winds are hence referred to as prevailing winds as well. Westerlies, easterlies, and trade winds are called primary winds.

Westerlies

Westerlies are also called anti-trade winds. These blow from the west and hence get their name. They arise at the high-pressure region in the horse latitudes i.e. 30 degrees north and 30 degrees south of the equator and flow towards the polar regions. These winds blow from the southwest direction in the northern hemisphere and from the northwest in the southern hemisphere. These winds are responsible for controlling and directing the movement of extratropical cyclones.

Polar Easterlies

Polar easterlies are dry, cold winds that arise at the poles and move toward the equator. They blow from northeast to northwest in the northern hemisphere and from southeast to southwest in the southern hemisphere.

Trade Winds

Trade winds are also known as tropical easterlies as they blow from the tropics toward the equator in the same direction as the easterlies. The deflection of these winds towards the west is credited to the Coriolis effect. Trade winds limit themselves within the 30 degrees north to 30 degrees south latitudes. The trade winds from both hemispheres collide at the equator, resulting in heavy rainfalls in these regions.

Periodic winds

Periodic winds are those winds that occur during a particular time of the year in a particular region. These winds tend to change their direction with the season and are mainly affected by the physique of the geographical area. The most popular example is the Monsoon winds.

Monsoon Winds

Monsoon winds are the moisture-laden winds that are responsible for bringing in high rainfall in the Asian sub-continent. Monsoon winds arise when a low-pressure area develops in the tropical region of the northern hemisphere during summers and pulls the southwestern trade winds towards the tropic. Since these winds traverse large water bodies, they become moisture laden. The Coriolis effect causes these winds to bend right and strike the west coast of the Indian landmass resulting in the summer monsoon. The condition reverses in the winter as a high-pressure region develops in the north Indian landmass and these winds start travelling south towards the equator. During this time they cause rainfall on the eastern coasts of the Indian subcontinent along with regions of China, Myanmar, Bhutan, etc. During this time they are called winter monsoons. The monsoon winds blow across the Arabian sea, India, Pakistan, China, Bangladesh, Myanmar, Sri Lanka, the Bay of Bengal, the Indian Ocean, southern Asia, and northern Australia.

Local Winds

Local winds are those winds that arise in a particular geographical region for a very short span. Land breezes, sea breezes, mountain valley breezes, and desert winds are examples of local winds. These winds have characteristics contributed by the local climatic conditions like temperature, topography, etc. Chinook, Foehn, Bora, and Loo, are names of some local winds.

Desert Winds

Desert winds blow in the desert regions due to the development of the low-pressure region in the area during the day. These winds are dry and dust-laden. One of the popular examples is Loo blowing in northern India during summer.

Land Breeze and Sea Breeze

Land breezes and sea breezes are also considered under the periodic winds. Land breezes and sea breezes arise near the sea shores due to differences in air pressure over land and sea. Land breezes occur during the night when the cool wind from the land moves towards the sea and sea breezes occur during the day when cool air from the sea moves to the land. Land breezes and sea breezes are responsible for the moderate climate of the shore cities.

Mountain Breezes and Valley Breezes

Mountain breezes arise during the night when cool air from the mountain slopes moves towards the warmer regions of the valleys. Valley breezes occur during the day when the mountain slope gets warm pulling the cold air from valleys to the slope. These winds are also considered periodic winds.

Variable Winds

Variable winds occur when weather changes cause disturbances in the prevalent winds. Cyclones, anticyclones, and storms are resultants of variable winds.

Recommended Articles:

Uniform and Non-Uniform Motion
Unit Conversion
Unit of Capacitance
Unit of Conductivity
Unit of Density