Planetary Winds- Mountains and Valley Breeze

Mountain and valley breezes are under wind types. They help influence temperatures in surrounding areas, as well as other types of winds. Planetary winds, however, are much larger and span larger regions.

What are Planetary Winds?

Winds are currents of air that move from one direction to another. They usually move from areas of high pressure to areas of low pressure with high velocities and a specific direction; hence their direction can be gotten from a wind vane(antique method though).

Winds are classified as either 

• Permanent Winds
• Seasonal Winds
• Local Winds

On the other hand, planetary finds are winds that ebb(move) all year round from one latitude to another latitude; mostly due to variations in latitudinal air pressures.

Characteristics of Planetary Winds

All planetary finds follow general patterns of movement such as

•  Movement from East to West

This is because of the rotation of the earth(which occurs in an ) and generates an effect called the Coriolis effect.

The Coriolis effect, in simple terms, is a phenomenon caused by an inertial force, the Coriolis force, which makes entities such as air currents that travel for long distances around the Earth move in a curve rather than a straight line.

This is caused by a single principle: when objects are in motion, relative to Earth’s rotational movement, a force will be acted on them pushing them to the left; hence we see a deflection in their movement and it is termed the Coriolis effect.

• They blow from regions of high pressure to regions of low pressure

• They move over a specific region or area on Earth’s surface eg trade winds

Classification of Winds

Winds are classified based on certain criteria.

• Based on global or local phenomena;

1. Primary Winds
2. Secondary Winds
3. Tertiary Winds

• Primary Winds

These are the continual and lasting winds that travel the earth’s surface. Planetary winds are good examples of this type of wind.

Examples of planetary winds are

• Trade Winds
• Westerlies
• Easterlies

• Secondary Winds

Secondary winds are winds that change their particular direction anytime there is a change in season; that is from summer to winter, etc. 

 They are also called periodic winds since seasons follow a periodic pattern. Examples are 

• • Monsoons

• Mountain and valley breezes

• Cyclones
• Anticyclones
• Air masses.

• Tertiary Winds

Tertiary or local winds are winds that move over small distances and areas. They are localized to specific parts of the world.

Examples are;

• Loo
• Blizzards
• Chinook
• Fohn
• Meltemi

Mountain and Valley Breezes

Mountain and valley breezes are connected, as both are formed due to temperature differences and gravity. 

Mountain breezes flow from the mountainside (a higher ground) to the valley(lower ground) while gallery breezes flow in the opposite direction.

They are different from land and sea breezes, which occurs over land and 

seas and is caused by temperature and pressure gradients. 

Concept of Land and Sea Breeze

Though the concept of how both mountain and valley breezes flow and land and sea breezes move are quite similar, there are still some differences to be found.

Inland and sea breezes, the cause is due to the absorption of heat by the land and sea. For land breezes, during the day, the land gets hotter and warmer than the surrounding sea. This causes the air flowing over the land to rise to transform it to a low-pressure region, while the sea is followed and pressure is higher.

Consequently, a pressure difference is created between these and the sea causing the breeze to move from the sea to the hand as a sea breeze. During the day, however, a situation occurs as the land loses more heat since the sun is out and becomes progressively colder than the sea and a pressure gradient is formed between the land and which makes a breeze move from the land to the sea, known as a land breeze.

Concept of Mountain and Valley Breeze

The cause of mountain and valley breeze is similar to that of land and sea breeze as said above. 

In the daytime, mountain air is heated up by the sun as the valley becomes cooler than the mountainside. Convection currents will be generated that will move the mountain air to move over the valley this is called the valley breeze.

In the night, the slopes of the mountainside get cooled, and denser air goes into the valley as a mountain breeze. 

Comparing Katabatic Winds with Mountain and Valley Breeze

Katabatic winds are winds that move down a slope due to the force of gravity. They are also called downslope winds hence the similarity with mountain and valley breezes.

However, katabatic winds only flow at night. This is because no radiation/heat is coming, thus higher planes of land are cooler than the surrounding areas.

The air at the slope then becomes rapidly cooler, causing a shallow layer of air that is to the surface to become cooler and since it becomes heavier than the atmosphere, it creates a thermally separate area of air 

The scope then helps to put out the force of gravity on the layer of air, causing it to flow down as what is called Katabatic Wind.

From this, we can see that both katabatic, mountain, and valley breezes are all caused by gravity, but katabatic winds can be stronger than mountain and valley breezes and are also primarily due to sloped land.

Conclusion

Mountain and valley breezes help move convection currents and cool surrounding areas so that they do not become too hot. These events are vital to the survivability of life on earth because if this cooling effect does not happen, life will be subjected to extreme temperatures day and night.