It’s easy to believe that climate and weather patterns are exclusively affected by the activities that take place on the planet. for example, if enough water vapor is generated, then there should be a corresponding increase in rain. That’s just how the water cycle works and the effect of the resulting condensation.
However, the concept of sudden stratospheric warming presented below flips that concept on its head. The beauty of the way the information below is presented is its simplistic accessibility without any compromise on accuracy.
So, not only should you be able to digest the data with no problem, but you such also be able to share these important insights with those you care about effortlessly.
Sudden Stratospheric Warming Definition: What Is a Sudden Stratospheric Warming?
As the name suggests, these events take place in the stratosphere. Effectively, there is a rapid increase of temperature somewhere between 10 and 50 kilometers above the earth’s surface. The temperature recorded tends to fall within the range of 50 degrees Celsius.
Of course, at that kind of height, humans are unlikely to feel the warming portion of the phenomenon. Instead, it’s the effects that propagate down to the planet that are felt.
Occurrence of Sudden Stratospheric Warming in Winters
During the winter season, you find that there are strong westerly winds that are centered around the artic polar region in the stratosphere. This occurrence is called the stratospheric polar vortex.
The way it happens is not always consistent, and you sometimes find that the winds are weaker or their direction from west to east is reversed.
Remember that warm air cools as it rises, so the opposite happens when cold air descends. The cold air associated with the polar vortex finds itself moving downward incredibly quickly, which causes the rise in temperature in the stratosphere.
As this happens in the relatively short period of a few days, the term sudden stratospheric warming is used.
Types of Sudden Stratospheric Warming
When the polar vortex breakdown occurs, meteorologists tend to classify it in one of several ways. The first three covered below are the most common classification types used. However, sometimes, you may find that the Canadian category is introduced when a unique structure is observed.
The major classification label is used based on when the westerly wind reverses. These winds tend to be at 60N and 10 hPa. They effectively become easterly winds, which means there is a total polar vortex disruption. Additionally, you find that the said vertex either becomes displaced or is broken into daughter vertices.
Minor warnings retain similarities to their major counterparts. However, they are notable for managing to be less dramatic. The traditionally westerly winds in this case do not become easterly, but they do slow down. Therefore, the kind of disturbance that the major warnings are known for i.e., the breakdown, never happens.
The way the stratosphere’s radiative cycle is supposed to flow is well established. There is supposed to be a westerly mean flow during the winter and a corresponding easterly flow during the summer.
When final warming happens, you find that the polar vortex winds end up changing direction. A switch back to the normal flow does not happen until the next winter. Additionally, this tends to happen when the stratosphere transitioning to its summer easterly phase.
Another warming cannot take place during summertime, so it is called the “final” warming since it’s the last one of the current winter.
These warnings are notable for their occurrences in the northern hemisphere’s stratosphere. They are typically seen during the period of mid-November to early December. There is no counterpart towards the south.
Characteristics of Sudden Stratospheric Warming
Notable characteristics are as follows:
- Bimodal amplitude distribution
- Small amplitude warmings during early and late winter
- Large amplitude warmings during mid-winter
Nature of Sudden Stratospheric Warming in Atmosphere
You tend to find that the planetary waves responsible for sudden stratospheric warming formation have larger amplitudes in the northern hemisphere than they do on the southern side.
Research would indicate that the difference in the way the planet’s physical features (land, mountains, sea) are distributed between both hemispheres partially accounts for this.
Waves tend to be fed by contrasts in temperature between the land and ocean. Mountains channel the flow of wind, so they also have a part to play in the mix.
All these factors occur more in the north than they do in the south, which means you tend to find the phenomenon occurring in the northern hemisphere. You should note, however, that there was once a strong one observed in the southern hemisphere in September 2002.
Effects of Sudden Stratospheric Warming on Weather Conditions
Whenever sudden stratospheric warming happens, you find that it can cause the jet stream to start to snake. When this happens, a massive blocking high-pressure area is observed. It can often be isolated to Scandinavia and the North Atlantic.
This spells a long period of cold, dry weather for Northern Europe, while southern Europe gets wet, windy, and milder weather.
The border of these two locations sees cold easterly winds and sometimes even see snow from the drop in temperature.
Is It Possible to Predict Sudden Stratospheric Warming in Advance?
Technology is currently at a stage where it allows the prediction of individual southern stratospheric warmings somewhere in the realm of a week before they happen. Satellite and other indicators tend to tell the story.
This allows for an analysis of how they may develop and predictions of the potential effects on future weather. There are usually a few weeks up to a month before the said effects on the weather begin to happen.
Facts about Stratospheric Warming
Here are some facts about this occurrence:
- Waves can only move around the earth’s atmosphere in westerly winds
- Weather fluctuations send waves to the easterly winds in the stratosphere
- When winds can no longer travel further, they reinforce easterly winds and bring them lower
- Eventually, they move down to the lowest point of the atmosphere i.e., the troposphere, which is where the planet’s weather is.
When the polar vortex that circles about the Arctic polar region is disturbed, you find that sudden stratospheric warming may occur. The extent of that disruption and the time at which it occurs feed into the classifications provided.
Now that you know about the inner workings of this pattern, why not share it with your friends, so they can also observe future occurrences with greater understanding?