# : 552 value -

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## 552 value

### #1snowflake

• Group: Members
• Posts: 1540
• Joined: 23-December 02
• LocationIOW

Posted --

Why is it that on the 500mb thickness charts there is a pronounced demarcation at the 552 value (a change from yellow to green and a thick black line). It isn't Evan a 1000-500 value. It cant be where the polar front or jet stream live, all I can think of is that it gives a rough guide to boundary between the warm and cool air masses (polar front again?)

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### #2Dave W

• Group: Executive
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• Joined: 17-October 03
• LocationBrighton

Posted --

I dont think it means anything especially..
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### #3PaulKn

• Group: Chasers
• Posts: 19950
• Joined: 08-March 03

Posted --

I agree - I think it's just an arbitrary value taken as the swap-over for the different colour schemes...I suppose you could say that typically colder airmasses are below that value, and warmer ones above, but you could equally well pick a different one!
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### #4snowflake

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• Joined: 23-December 02
• LocationIOW

Posted --

Thanks Dave and Paul
It just seemed to my untrained eye that it signified something that I was missing, thanks again
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