The Swirls and Deformation Zone Revisited

#2361 "Singleton Sunset Swirl"

Our reality really depends on our point of view – our vantage point. We live on a spinning Globe and this requires that we view our non-inertial frame of reference using our Coriolis Hand. I wrote about this in more detail in The Solution to Cloud Swirls Can Be Found in Your Hands.

Cloud shapes are formed within the free atmosphere that covers our spinning Globe. There are low clouds that are influenced by their life in the planetary boundary layer but we have not talked about them yet. The best vantage point to view and understand the lines and swirls is from the atmosphere itself. In Cloud Shapes and Lines in the Atmosphere , I described how cloud shapes develop and how it is so much easier to understand them from a frame of reference attached to the mean flow of the atmosphere. 

A simple, straight line deformation zone forms with just a decrease in the wind speed as viewed from a vantage attached to the earth. That subtle change in wind speed is difficult to observe but the line that it creates is extremely obvious - which is the rationale behind the deformation zone conceptual model. That Blog goes into more detail with many  more graphics. The average winds with respect to the atmospheric frame average to zero to create a straight line deformation zone. 

If you want to paddle your canoe forward though, the atmospheric frame winds cannot average to zero and one creates a bowed shape deformation zone like we saw in the pool of duckweed in  Gravity Waves and the Deformation Zone.  

Let’s revisit the straight line deformation zone in terms of your Coriolis Hand to make certain we have these concepts firmly in hand. I made some "brains hurt" and I am sorry for that and want to do better. The fingers of your Coriolis Hand can only bend one way and aline with how the flow also swirls. 

If you point the thumb of you Coriolis Hand upward at every X, your fingers must curl in the direction of the flow. 

Northern Hemisphere Right Coriolis Hand
with Thumb pointing Up and
my Fingers Curled Cyclonically

If you point the thumb of you Coriolis Hand downward at every N, your fingers must curl in the direction of the flow. 

Northern Hemisphere Right Coriolis Hand
with Thumb pointing Down and
my Fingers Curled Anticyclonically

If you already know the direction of the flow, point the fingers of your Coriolis Hand in that direction. Your thumb must point in the direction of the vertical motion in the atmosphere. 

I have created a Coriolis Hand graphic to assist. These graphics were created to correspond with the view looking down from space toward the weather pattern or the pool of duckweed. 

The deformation zone conceptual model is an extremely powerful tool to thoroughly analyze and diagnosis the weather. Given a single line or any one of the four swirls, you can recreate the other four components as well as the the opposing winds along the axis of contraction (purple arrows above). The shape of the deformation zone reveals the relative strengths and characteristics of the swirls and opposing winds. In turn it reveals almost everything about the weather situation. I will leave this discussion for the next Blog. 

But the weather is three dimensional. We are confined to a flat surface in this Blog but if you look toward the 3D deformation skin along the axis of contraction, you will see that the swirls as depicted above are just quasi-horizontal cross-sections through the 3D smoke ring formed by the wind blowing toward the col. I have showed this vertical cross-section of the smoke ring before but it might make more sense now... Use you Coriolis hand and follow the ring around the puff of air blowing into the page at the centre of the ring. 

Next week we will look after different shapes of deformation zones and diagnosis what they mean. 

In #2361 "Singleton Sunset Swirl", the cloud behind the approaching deformation zone was drifting to the right. There were even some wind gravity waves embedded in the gravity swells that I described in Seeing Even More Gravity Wave Clouds. I imagined that I was within that cloud,  and pointing the fingers of my Coriolis Hand to the right forced my thumb to point upward. This made sense because the rising atmosphere would also support all of the cloud that I saw and painted. The cyclonic companion of the warm conveyor belt was approaching with more clouds and more weather. The col of the deformation zone was somewhere off to the left. I was looking toward the west and the setting sun so the col of the deformation zone was to the south of Singleton. Hope this helps... 

Keep you paddle in the water and warmest regards... 

Phil the Forecaster Chadwick