The term “Jet Stream” is a very popular term among the weather forecast enthusiasts. If you’re a regular viewer of weather news, you might have heard this term so many times.
Although this is a very common term, most common doesn’t know what is a jet stream and how does work. You might even ask a bigger question – how does jet stream affect weather?
In this article, I’ll try to give you a detailed analysis on jet stream, so that you can understand very clearly how this natural phenomenon affects our weather pattern.
What is Jet Stream?
First of all, let’s look at what a jet stream is.
Technically speaking, the jet stream is the rivers of speedy moving wind in the lower layer of our atmosphere. In other words, the jet streams are the bands of strong air currents in the troposphere.
Generally, jet streams are formed at the boundary lines between opposite air masses. These opposite air masses have two distinctive characteristics – pressure and temperature.
You might know that warm air masses are located in high pressure zones and cold air masses in the low pressure zones.
As a result of the difference in pressure and temperature, the warm air masses flow from high pressure zones to low pressure zones, and eventually cools down. This process creates strong currents that are termed as jet streams.
Location, Direction & Speed
Jet streams are generally formed in the troposphere around 6-9 miles above the ground. You would be surprised to learn that the jet streams are thousands of miles long, hundreds of miles wide and several miles thick.
There are several jet streams and most of them travel from west to east just as the Earth rotates on its axis. And they travel in a wave shaped pattern due to different pressure zones.
Known as Rossby waves or planetary, the large waves of the jet streams drift cold air towards south and warm air towards north.
The jet streams are really strong wind. Naturally, these currents flow at a speed of nearly 200 miles per hour. So, you can easily imagine how strong they are!
Another important thing you should note that the location and speed of the jet streams changes along with the season.
As the cold air is comparatively heavier, the jet stream in the northern hemisphere flows at a comparatively low height in the winter. During this period, the stream brings cold air from the polar region along with it.
This polar jet, on the other hand, start to move towards north in the spring. And during the change of its course, it also steers the high and low pressure zones along with it.
The Polar & Subtropical Jets
As I’ve mentioned earlier that there several jet streams in our atmosphere. These streams can be divided into two categories – the polar jet and the subtropical jet.
You should know that the southern hemisphere and northern hemisphere each have polar and subtropical jets.
Polar Jet: The jet that is formed in the polar region is generally termed as polar jets. These jets are commonly known as the mid-latitude jets in North America as they occur over that latitude.
Subtropical Jet: Similarly, the jet located in the subtropical region is known as subtropical jet.
There are some basic differences among these two types of jets. The polar jets occur at a low altitude as they are formed of cold air masses, while the subtropical jets occur at higher altitude as they are formed of warm air masses.
Here’s a video on everything you need to know about Jet Streams
How Jet Stream Affects Weather
Although the jet streams occur at a high altitude, they can have substantial influence on our weather. However, to what extent the jet streams will affect weather depends on some factors. Let’s have a look at those factors.
Altitude of the jet, difference of temperature and different pressure zones are the factors that will tell you how much a jet will affect the weather. However, you must keep in mind that all these are factors are inter-related.
Let’s consider the polar jet of northern hemisphere to understand the effect of jet on weather. You should also look closely how the mentioned above three factors influence each other.
In the winter, the polar jet brings along cold air masses from the polar region. As a result, it is natural that this jet will occur at a low altitude due to heavy air masses.
You also know that the speed of this jet current is the strongest at the boundary lines of different pressure zones. And the pressure zones are created due to difference of temperatures, right?
So, you probably can guess that the polar jet is more likely to cause severe weather conditions in the low pressure zones. By severe weather conditions, I mean rain, storm, etc.
And, we’ll feel the drastic change in weather as the jet stream is comparatively closer to the Earth’s surface.
So, it is needless to say that the subtropical jets that occur at a higher altitude will have less influence on our weather than the polar jets.
Finally, I would like to admit that I’ve tried my best to explain the jet stream and its effects on weather in the simplest possible terms. Hopefully, you’ll get a clear idea about the jets streams.
In a nutshell, although the jet stream cannot be seen in open eyes, they exist for real. And the jet streams are responsible to steer different weather conditions from place to place.