You’ve vortex is strong, meaning there is

You’ve probably never thought much about the Arctic Oscillation or the North Atlantic Oscillation, but these weather phenomena impact global climates. This lesson explores each oscillation and describes the weather patterns associated with them.

Arctic Oscillation

When you say ‘Arctic’ a lot of things come to mind, like cold weather and maybe even the North Pole with flying reindeer, elves and Santa Claus. But Arctic Oscillation probably isn’t one of the images that pop into your brain.So what is this ‘Arctic Oscillation?’ Picture a teeter-totter.

Our Authors Write a Custom Essay
For Only $13.90/page!


order now

First, one side is up and the other is down, then one side is down and the other is up. The Arctic Oscillation is a lot like a teeter-totter, but instead of people bouncing up and down, you have changes in pressure and weather.The Arctic Oscillation (AO) can be described as changes in pressure between the arctic and mid-latitudes. These pressure changes result in wind and weather changes. There are two different phases in the Arctic Oscillation: the positive phase and the negative phase.

You can think of the positive phase on one end of the teeter-totter and the negative phase on the other end. These phases oscillate, or teeter back and forth all of the time.A couple of things before we delve into these phases. Wind blows from high to low pressure, and the greater the difference between the pressures, the faster and stronger the wind. If you can remember, winds blow from high to low, you will have an easier time navigating the oscillations in this lesson. Finally, winds are named based on where they originate. So, if you have westerlies, you can assume the winds blew from the west.

Okay, let’s get started!

Arctic Oscillation Phases ; Impact

The Arctic Oscillation is based on two pressure systems: one over the arctic and one over the mid-latitude region. Now, a little on the arctic pressure system before we go on. There is a continual pressure system in the arctic known as the polar vortex. In the positive phase, the polar vortex is strong, meaning there is a strong low-pressure system in the arctic. Meanwhile, the pressure system at the mid-latitudes is high.

Remember: winds blows from high to low so this causes winds to blow from the mid-latitudes to the arctic. This causes fast moving westerly winds and northeasterly trade winds, which trap the cold air in the arctic.Before we check out how the positive phase of the Arctic Oscillation impacts Santa and his crew, let’s check out the negative phase.

During the negative phase, the polar vortex is weak, which means the pressure system is higher than normal in the arctic. And the high-pressure system in the mid-latitudes is lower than normal. Because the difference between the high and low-pressure systems isn’t as great as it is in the positive phase, the winds are not as strong or fast. Also, because the high-pressure system is now in the arctic and the low-pressure system is in the mid-latitudes, the wind will flow from the arctic to the mid-latitudes.

Because both of these factors, the winds lollygag along, which causes ridges and troughs. This allows the cold, arctic air to flow southward.Now that you have a little background, let’s see how these phases impact the weather. It’s worth noting that this list of weather patterns doesn’t address every weather pattern impacted by the Arctic Oscillation, but it does allow you to get the general patterns.

Let’s start in Canada and Greenland and work our way across the globe. Check out the table to help you keep all of the weather patterns straight. During the positive phase, Canada and Greenland experience colder-than-normal temperatures because the cold, arctic air gets trapped.

During the negative phase, however, the cold air travels further south, so Western Greenland and Eastern Canada experience mild temperatures.Next, let’s head over to Asia and Northern Europe. During the positive phase, these regions experience warmer temperatures and increased precipitation; however, during the negative phase they experience colder-than-average temperatures. Next, the Mediterranean experiences droughts in the positive phase and increased storms in the negative phase.

Finally, let’s head to the United States. In the Eastern United States, there are warmer temperatures during the positive phase and colder temperatures with storms on the Northeastern coast. And on the West coast, a positive phase causes warm and dry conditions and the negative causes cold conditions. And we can’t forget about Santa.

Because he is in the arctic, he will experience colder-than-normal conditions during the positive phase and warmer-than-normal conditions during the negative phase.

Location Positive Negative
Canada and Greenland Cold temperatures Mild in Western Greenland and Eastern Canada
Asia and Northern Europe Higher-than-normal temperatures and precipitation Colder-than-normal temperatures
Mediterranean Dry Increased storms
Eastern U.S.

Warmer-than-normal temperatures Colder temperatures and increased storms on the Northeastern coast
Western U.S. Warm and dry Cold

North Atlantic Oscillation

Believe it or not, the Arctic Oscillation isn’t the only weather pattern that acts like a teeter-totter. The North Atlantic Oscillation (NAO) is another weather pattern, but it is the fluctuation in pressure over the North Atlantic Ocean.

It affects weather patterns around the world. Like the Arctic Oscillation, the North Atlantic Oscillation has a positive and a negative phase. The North Atlantic Oscillation has two pressure systems: one over the Azores, which is a high-pressure system, and one close to Iceland, which is a low-pressure system.

North Atlantic Oscillation Phases ; Impact

During the positive phase the Icelandic low-pressusre system, also termed the Icelandic Low, gets really strong and the Azore high-pressure system, also termed the Azores High, gets really strong. This causes a huge difference between the high- and low-pressure systems, which causes the westerlies to get really strong. The strong westerlies prevent cold air from blowing south.

Instead, the cold air heads towards North America. Sounds familiar doesn’t it? Even though it’s a different part of the world, the North Atlantic Oscillation works in much of the same way as the Arctic Oscillation.A negative North Atlantic Oscillation occurs when the Icelandic Low is higher than normal and the Azores High is lower than normal.

Both of these pressure systems are much weaker than they were during the positive phase. This causes less of a difference between high and low pressure so the winds are weak. The weak winds allow cold air to escape southward.

Let’s see how the North Atlantic Oscillation impacts the weather. Again, this table doesn’t address every single weather pattern associated with the Arctic Oscillation, but it will give you the general idea.In the Eastern United States, a positive North Atlantic Oscillation results in warmer temperatures and less storms, whereas a negative phase results in colder-than-normal temperatures and increased storms. Remember, it’s like a teeter-totter so you can expect the phases to create opposite weather effects: when it’s hot during one phase, it’ll be cold during the other phase. In Northern Europe, the positive phase brings warm temperatures, increased storms and increased precipitation.

And, if the negative phase is opposite, you can probably guess how it impacts Northern Europe, right? Yep, colder than normal temperatures with less storms and precipitation. Finally, Southern Europe experiences decreased precipitation and fewer storms during the positive phase and warmer temperatures with increased storms and precipitation during the negative phase.

Location Positive Negative
Eastern United States Warmer-than-normal temperatures and less storms Colder than normal and increased storms
Northern Europe Warmer than normal and increased precipitation and storms Colder than normal and decreased precipitation and storms
Southern Europe Decreased precipitation and less storms Warmer-than-normal temperatures and increased precipitation and storms

Lesson Summary

From a chilly Santa Claus at the North Pole to a pressure system over the Azores, the teeter-tottering oscillations create changing weather patterns all over the earth. Let’s take a moment to review these oscillations.

The Arctic Oscillation occurs due to changes in pressure in the arctic and mid-latitudes and can be divided into the positive and negative phases. The positive phase occurs when the polar vortex has a strong low-pressure system, and the mid-latitudes have a strong high-pressure system. This causes strong winds that trap cold air in the Northern latitudes. The negative phase is the opposite of the positive phase, and the polar vortex has a higher-than-normal system and the mid-latitudes have a lower-than-normal pressure system.

This allows cold air to blow southward. Remember, these phases cause a variety of weather patterns, so take a moment to review the table. It gets a little confusing but a general rule is that a positive phase causes cold weather in the north and warmer weather further south. A negative phase causes warmer weather in the north and colder weather in the south. So, I guess it’s safe to assume Santa prefers the negative phase!

Location Positive Negative
Canada and Greenland Cold temperatures Mild in Western Greenland and Eastern Canada
Asia and Northern Europe Higher-than-normal temperatures and precipitation Colder-than-normal temperatures
Mediterranean Dry Increased storms
Eastern U.

S.

Warmer-than-normal temperatures Colder temperatures and increased storms on the Northeastern coast
Western U.S. Warm and dry Cold

Next we looked at the North Atlantic Oscillation, which is caused by changes in pressure above the North Atlantic Ocean. In this case, the pressure systems are located near Iceland and above the Azores. During the positive phase, both the Icelandic Low and Azores high are strong. This causes strong winds that prevent cold air from traveling southward.

The reverse happens during a negative phase, so the Icelandic Low is higher than normal and Azores High is lower than normal. This causes cold air to escape southward. Like the Arctic Oscillation, the North Atlantic Oscillation impacts weather. Take a moment to review the table.

Location Positive Negative
Eastern United States Warmer-than-normal temperatures and less storms Colder than normal and increased storms
Northern Europe Warmer than normal and increased precipitation and storms Colder than normal and decreased precipitation and storms
Southern Europe Decreased precipitation and less storms Warmer-than-normal temperatures and increased precipitation and storms

Again, it gets a little confusing but remember when it’s a positive phase, cold air gets trapped further north but when it’s negative the cold air escapes southward, just like it did in the Arctic Oscillation.

Depending on where you live, you might be wishing for different phases of both of these oscillations!

Learning Outcomes

When you are finished, you should be able to:

  • Describe the Arctic and North Atlantic Oscillations
  • Describe the phases of the Arctic and North Atlantic Oscillations
  • Discuss the impact of the phases of the Arctic Oscillation and the North Atlantic Oscillation on global climates
x

Hi!
I'm Sigvald

Do you need a custom essay? How about ordering an essay here?

Check it out