Mountain and valley winds: differences and definition

Introduction

Mountain and valley winds are classified as local winds. These winds are blowing only in the mountain and valley regions. Both mountain and valley winds are in the same category, but there are some differences between these two types of local winds. Below is a discussion of the differences between mountain and valley winds (1). Before discussing the difference between mountain and valley winds, let us know what is wind and their types. 

Winds are the movement of air parallel to the surface or horizontally (from a high-pressure area to a low-pressure area). The velocity of the wind depends on the rate of difference in the air pressure between the two regions. So it can be seen that the wind sometimes flows at high speed and sometimes slowly (2). 

The wind is created mainly due to variations in air pressure. The wind flows from the high-pressure area to the low-pressure area to balance the high pressure and the low pressure.

When the wind in a place gets too hot, it becomes lighter and rises. As a result of the rise of the hot wind, the air from the surrounding area rushes there to fill this void. Wind can be used in various ways for our day-to-day life activities. Such as drying clothes, sailing in the river, keeping the body cool, etc. Therefore, it can be said that the importance of wind in people’s daily life is immense.  

There are various types of winds. According to the type of origin and characteristics, the wind is basically divided into four main parts. These are planetary winds, periodical winds, local winds, and irregular winds. Mountain wind and valley wind belong to the local wind. Here we discussed valley winds and mountain winds (1) & (3).

What are mountain winds?

Mountains radiate heat at night, this makes the mountains cool. At this time the valley is relatively warm. As a result, cold and heavy winds blow down the mountain. The wind that blows at night towards the bottom of the valley is known as mountain wind (2). 

Example

This type of wind blows at night in the Kullu and Kangra valleys of Himachal Pradesh, India. The Foehn is the Alps Mountain in Europe, the Chinook in the Rocky Mountains, and the Zonda in the Andes mountains, etc. are examples of mountain winds. 

Interesting facts about mountain winds

• This type of wind flow continues from some time after sunset till sunrise. 
• Mountain wind speed is highest at night.
• It is mainly due to the unevenness of the land in the highlands.
• In the highlands, this type of wind is generated at night every day, but during catastrophic air disturbances (e.g. tropical cyclones) the normal flow of this type of air is disrupted.
• This wind blows down the valley at night.
• Mountain winds are cool and heavy.
• At night it descends down the valley, thus, is a downslope wind.
• This downslope wind is created when the mountain surface is colder than the surrounding air.
• Due to this wind, the bottom of the valley is covered in dense fog (2) & (4).

Impact of mountain wind

The lower part of the hilly region becomes relatively cold due to the effect of mountain winds. As a result, the weather becomes dry and as the night progresses, its intensity gradually increases. Naturally, this type of wind-affected mountain is relatively sparsely populated (2). 

What are the valley winds?

Due to the slope of the land, a special kind of wind flow is created in the mountain areas. During the day the mountains are warmer than the bottom of the valley. This causes high pressure at the bottom of the valley and low pressure at the side of the mountain. For this reason, the wind that blows upwards through the mountain during the day is called valley wind (1) & (2).

Example

Valley wind blows at a day in the Kullu and Kangra valleys of Himachal Pradesh, India. Santa Ana, Chinook, Diablo, Foehn, etc. are also examples of valley winds. 

Interesting facts about valley winds 

• Valley winds blow during the daytime in the highlands.
• This air flows in a convection process.
• The air is warm and light.
• This type of wind flow continues from sunrise to sunset.
• Valley wind’s speed is highest after some time in the afternoon.
• This wind is mainly created due to the topography of the land in the hilly areas. 
• It rises to the top of the mountain and after a short stay, it returns in the form of anti-valley wind. 
• In the highlands, this type of wind is generated during the daytime, but during catastrophic air disturbances (e.g. tropical cyclones) the normal flow of this type of air is disrupted.
• Due to this wind, the valley becomes cloudless.
• A valley wind is produced by rapid warming of the valley floor which expands the air and flows over the slope (2). 

Impact of valley wind 

Due to the effect of valley wind, the upper part of the mountain region is relatively warm, which makes the weather pleasant and comfortable. Therefore the population is relatively high in the upper part of such wind-affected mountains (2).

Differences between Mountain and valley winds

Mountain winds and valley winds both are not the same type of wind. Some differences are observed between mountain and valley winds. Their differences are discussed below.

Similarities

• Mountain and valley winds are the same class of wind. They both belong to the local wind.
• These two winds are caused by the difference in air pressure and heat.
• Mountain and valley wind both are controlled locally by the topography and environment.
• These two types of wind flow in a certain direction at regular intervals (1). 

Written By: Manisha Bharati

Q&A

1. Valley and mountain breezes are examples of what winds?

Valley and mountain breezes are examples of local wind (1). 

2. What is a mountain and valley winds 

Mountain wind

Mountain winds are the type of local wind that blows at night towards the bottom of the valley. It makes the weather dry. It blows at night time.

Valley wind

Valley winds are a type of local wind that blows up the mountain during the daytime. The valley wind flow makes the wind pleasant. It blows in the daytime (2).