Hale's Polarity Law and polarity reversal

[Newbie]

Given that there is a reversal of the polarities of sunspots when going from one solar cycle to the next, then for SC24: positive polarity was to the west, negative polarity to the east +/-  and for SC25: negative polarity was to the west, positive to the east -/+.

However is this true for southern hemisphere sunspots only? and is it true that polarities undergo a reversal in each hemisphere of the sun so that for the northern hemisphere the opposite is true SC24 -/+, SC25 +/- ?

 

[3gMike]

Yes that is correct.

A useful description of the mechanism involved can be found here https://svs.gsfc.nasa.gov/3583

Edit: It is worth noting that east / west references can be confusing, since the west side of the Sun is to the right of the image. It is more usual to refer to leading edge polarity, with direction of travel being left to right on the image.

Edited July 21, 2021 by 3gMike
Clarification of East / West

[Drax Spacex]

Every 11 years the Sun's magnetic dipole flips (north becomes south; south becomes north).  Along with it, sunspot polarities in each hemisphere also flip.

North magnetic polarity = +
South magnetic polarity = -

In SC24:
Northern hemisphere sunspots were +/-
Southern hemisphere sunspots were -/+

In SC25:
Northern hemisphere sunspots are -/+
Southern hemisphere sunspots are +/-

In a grayscale magnetogram,
+ is white.
- is black.

In a colorized magnetogram,
+ is green/blue.
- is yellow/red.

[Drax Spacex]

For a real mind scrambler, have a look at this movie.  It's an animation of the magnetogram for each Carrington rotation from September 2006 through this month.  Near the start of SC25 in early 2020 you can see the AR polarity reversal.

Carrington Rotation Magnetogram Synoptic Map Movie

At high speed, this animation could be subtitled "Clumps of sand rolling downhill in strong wind."

[Newbie]

5 hours ago, 3gMike said:

Yes that is correct.

A useful description of the mechanism involved can be found here https://svs.gsfc.nasa.gov/3583

Edit: It is worth noting that east / west references can be confusing, since the west side of the Sun is to the right of the image. It is more usual to refer to leading edge polarity, with direction of travel being left to right on the image.

Thanks for your reply. Yeah I get how using east and west can be confusing but this same convention is used when sunspots rotate over the east limb or sunspots rotate behind the west limb and is also used when the determining the co-ordinates of the  position of sunspots on the solar surface. Left to right is cool and if that's the usual way of talking about leading edge polarity, great!

3 hours ago, Drax Spacex said:

For a real mind scrambler, have a look at this movie.  It's an animation of the magnetogram for each Carrington rotation from September 2006 through this month.  Near the start of SC25 in early 2020 you can see the AR polarity reversal.

Carrington Rotation Magnetogram Synoptic Map Movie

At high speed, this animation could be subtitled "Clumps of sand rolling downhill in strong wind."

Drax Spacex that's a great movie! played at high speed couldn't help thinking I was at the beach. Also very much appreciated the listing of the polarities for both hemispheres. 

Thankyou