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atmospheric pressure


Iron_angling

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3 minutes ago, carpepecheur said:

I have had my best results in settled high pressure, with clear blue skies, and bright sunshine.

 

---- But I live in SW France and that is typical summer weather here!

interesting. See i'm always told that in the UK low pressure is best but I wouldn't have a clue tbh..

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6 minutes ago, Iron_angling said:

I always see people saying the pressure today is too low/high. 

what pressures are best for carp fishing? any advice would be greatly appreciated.

Imo pressure has nothing to do with how good or bad a water might fish. What does have a huge influence is the weather conditions that low and high pressure systems bring.

In summer high pressure usually brings high temps with no wind - conditions that tend to see carp sunbathing rather than feeding. Low pressure systems (in summer) tend to bring big winds, overcast days and rain - perfect for getting the carp feeding.

In winter high pressure can be good - it normally brings bright sunny periods which provide the warmth the carp crave at this time of year. Zigs can be a killer in this situation as they're on the move in the upper layers. Low pressure can still be great depending on temps.

Some guys believe that pressure will dictate there the carp are in the water column (i.e. in high pressure they'll be up in the water and in low pressure they'll be on the deck). This is a load of tosh. The carp will be up in the water when they need warmth and it's sunny (which normally coincides with high pressure) and they'll be on the deck to feed (which normally happens when the conditions get them moving (big winds, overcast skies).

Of course, these conditions are not always guaranteed. It can rain during periods of high pressure and it can be bright during periods of low pressure. Hence, the pressure itself has very little influence.

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8 minutes ago, yonny said:

Imo pressure has nothing to do with how good or bad a water might fish. What does have a huge influence is the weather conditions that low and high pressure systems bring.

In summer high pressure usually brings high temps with no wind - conditions that tend to see carp sunbathing rather than feeding. Low pressure systems (in summer) tend to bring big winds, overcast days and rain - perfect for getting the carp feeding.

In winter high pressure can be good - it normally brings bright sunny periods which provide the warmth the carp crave at this time of year. Zigs can be a killer in this situation as they're on the move in the upper layers. Low pressure can still be great depending on temps.

Some guys believe that pressure will dictate there the carp are in the water column (i.e. in high pressure they'll be up in the water and in low pressure they'll be on the deck). This is a load of tosh. The carp will be up in the water when they need warmth and it's sunny (which normally coincides with high pressure) and they'll be on the deck to feed (which normally happens when the conditions get them moving (big winds, overcast skies).

Of course, these conditions are not always guaranteed. It can rain during periods of high pressure and it can be bright during periods of low pressure. Hence, the pressure itself has very little influence.

that's really interesting. thanks for the info. very much appreciated.

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19 minutes ago, yonny said:

Imo pressure has nothing to do with how good or bad a water might fish. What does have a huge influence is the weather conditions that low and high pressure systems bring.

I couldn’t agree more Yonny.

The mistake some people make is that they attribute what they are observing to the fact that the carp DETECT a change in pressure and ACT accordingly. For example I have heard some people say fish rise to the surface in high pressure to relieve the uncomfortable pressure it has on their swim bladders. Or during low pressure they drop to the bottom and start feeding there. They may be observing a valid correlation but they are mistaking the cause. If you start basing your observations on incorrect assumptions then you run the risk of going in the wrong direction to further your knowledge.

It is important to understand the difference between atmospheric pressure and hydrostatic pressure. Atmospheric pressure is the pressure you and I experience in the air at the bankside. Hydrostatic pressure is the pressure experienced by a fish under the surface of the water.

There is a connection between the two but it is not a direct correlation. In other words 1 mbar increase in atmospheric pressure does not result in 1 mbar increase in hydrostatic pressure. There is an increase in the latter but it is much smaller. The difference arises from the fact that air is a compressible fluid and water is an incompressible fluid.

So how much does pressure change during a storm? Well obviously it varies greatly depending on many variables but we need something to work with. Looking at a world meteorological forecast at the time of writing, the highest pressure I can see is 1025 Mbar and the lowest 975 Mbar so I guess that represents a fairly extreme weather pattern that we are unlikely to experience in UK. Just for information, on the same day in the UK the highest pressure is 777 Mbar and the lowest is 768Mbar. I am not being too precise here I am just trying to get a ball park figure for the highest change of pressure we can expect in a storm which seems to be around 50 Mbar.

Using very simple physics, If there was no atmospheric pressure, the hydrostatic pressure on the surface of a lake would equal 0

At 0.5 metres depth the hydrostatic pressure would be 49.05 Mbar.

But we have to add the atmospheric pressure to those values which is changing with the weather. And that change, in very extreme conditions, can be as much as 50 Mbar

That means that under extreme conditions the atmospheric change above the surface only represents a hydrostatic change of 0.5 metres.

Don’t take my figures, get your own from the weather forecast or from a barometer. Take the maximum and minimum values at your fishing location and then relate that difference to a difference in depth using 50 Mbar change in pressure = 0.5 metres in depth. (for Luddites still using imperial measures you can make your own conversion)

So here is the whole deal. Whatever sensation a carp experiences from a change in pressure due to weather e.g. 50 Mbar it is EXACTLY THE SAME as the sensation it would experience by changing the depth at which it swims by 0.5 metres.

But that is not all. That change does not take place instantly. It can take several hours for a weather front to move over your location so the actual change in sensation the fish experiences takes place VERY gradually.

This means that even if the carp is ultra-sensitive to pressure change it only has to adjust its depth by a very small amount to compensate for that change.

The reason that we attribute change In behaviour in how a carp behaves as a result of changing pressure is NOT because it experiences it directly but as a result of other factors that also change with pressure which may be temperature, wind strength, lighting conditions etc etc. Only by understanding this can you develop a true understanding of what is affecting the carp. Pressure change is universal in a given region but temperature, wind, light etc. etc. may vary more locally from lake to lake and even swim to swim. 

Of course if you fail to catch fish by not understanding this you can always blame your failure on the pressure change which you can do nothing about.

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8 minutes ago, carpepecheur said:

Of course if you fail to catch fish by not understanding this you can always blame your failure on the pressure change which you can do nothing about.

Lol, standard.

We had record high pressure here just a couple of weeks ago (~1050 mbar!!).

https://www.bbc.co.uk/news/science-environment-51180211

My mate was on the bank and got the first take he'd had in several weeks. Off the deck too. That tells us all we need to know about how pressure itself affects fishing.

Edited by yonny
typo
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It is the usual case of jumping to the wrong conclusion. A friend of mine was about to retire abroad but his family had a history of cancer. He consulted a WHO report which listed the countries with the lowest death from cancer, Sure enough there was one country that stood out as having the lowest death rate from cancer. ------- Syria!

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4 hours ago, Iron_angling said:

Morning guys,

 

I always see people saying the pressure today is too low/high. 

what pressures are best for carp fishing? any advice would be greatly appreciated.

 

regards,

 

Josh

High pressure at work always makes me want to go fishing...😖😆

 

Seriously, I don't care the weather pressure or even the weather itself, the only way you will catch is if you go fishing.

This year I had my best catches in strong south westerlies that brought rain. The bivvy and everything got wet at times, but catching big fish from an unknown water made up for it

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5 hours ago, yonny said:

Lol, standard.

We had record high pressure here just a couple of weeks ago (~1050 mbar!!).

https://www.bbc.co.uk/news/science-environment-51180211

My mate was on the bank and got the first take he'd had in several weeks. Off the deck too. That tells us all we need to know about how pressure itself affects fishing.

Currently on 1031 where I am yesterday was 1035 so it is falling 

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Yonny has pretty well summed it up. If you get a sustained period of high pressure, i.e. sunny and warm with little wind, things can go a bit stale. A strong South-Westerly bringing warm rain can stir things up and so looking at the forecast for the next few days and acting on it can bring dividends. I fished for barbel a lot in the winter for many years and always tried to get out when the water temperature was on an upward ramp as it really did bring the fish on.

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9 hours ago, dayvid said:

The one thing I dont like and has noting to do with pressure , is the Moon , I tend not to catch as well during a Full moon  and I guess this also has a physiological effect on my fishing .

The same mate. 

If ever I'm night fishing and the moon is bright enough to cast a shadow I just know I'm not gonna catch. 

And I also get very hairy lol. 

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Atmospheric pressure plays a part, but only a part is what fishing will be like.  There are so many factors in play from temp to feed to disturbances both natural and un-natural as well as the solunar tables, not to mention what the angler is doing, that it's just another thing to consider, or not.  I've seen days when every single thing was indicating no fish, but the baitfish they love to eat were shoaling up against a point and they did everything but crawl onto the beach to get at them.  Likewise there will be perfect days when you know they're there and you should be catching like they're for free, and you do everything right and still can't buy a bite.

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  • 3 weeks later...

It was a new moon last night and the lake was fishing its head off, 3 for one guy, 3 for another including the big girl at 41lb, one of the kois came out and even I caught one 😁

Pressure has been dropping steadily but I can't help but be drawn by moon phases, I try and fish whenever I can but I will pester Mrs Putney more if it happens to be a new moon, I haven't made any decision on pressure yet but I do like a new moon 🎑

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