Trying to understand sea breezes, please help!

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yachtmilos

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In an article I read online the following was written about sea breezes and a trip round Britain:

'When the sun heats the air above the land, it causes another set of atmospheric quirks, the most obvious being sea breezes that weaken or reverse the offshore winds. In many places the resulting winds veer during the day, tending to blow with the coast on their left, and the sea breeze effect can also influence a light onshore wind by increasing its strength and inducing a similar veer. This means that in fine weather the winds near the coast will often display a bias towards blowing anticlockwise around the land.'

Can anyone help to unpack this please? I understand the basics of a sea breeze, but not the veering bit i.e why this happens?
Also, in my mind veering means to turn to the right, so wouldn't this mean creating a headwind for going anti-clockwise? Can someone please explain how the sea breezes aid an anti-clockwise passage? And is it true that there is an anti-clockwise bias? Later in the article it says this:

'Our experience suggests the anticlockwise bias of sea breezes will make a difference for nearly half the trip'

...which indicates to me that there is more than half the trip that is not helped by the bias?

Clearly I am very confused. Any help, explained simply, would be much appreciated.
 
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The land will effectively form a localised low pressure system, so if you stand with your back to the wind and in the northern hemisphere the low pressure zone will always be to your left side (Coriolis effect), so this does correlate that the wind would in fact veer (to the right) if it were blowing directly on shore prior to the influence of the sea breeze.
 
If you sail far enough offshore they won't affect you. Ultimately, they can be used to your advantage if you know how to use them.
 
When the sun heat’s the land, the land in turn heats the air above it. The hot air rises and draws in cooler air from the sea. That’s the sea breeze that you’ll find up to a few miles offshore.
If enough air rises it can overcome or reverse the effect of a prevailing offshore wind.
On a warm sunny day, you will first notice the offshore breeze dropping before its direction reverses to onshore in late morning or early afternoon.

Also, the air that has risen above the land will be sucked out to sea at high altitude to replace the lower air drawn inland from the sea. This will cause a band of cloud to form out at sea roughly parallel with the coast.
In other cases fog can form at the coast where the incoming cold air mixes with the warm air.
 
pvb said:
Nobody understands winds. Even the Met Office doesn't.
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Well not much help to OP but around here (32S 135E) with consistent sunny weather for 6 months we get remarkably consistent sea breezes. The coast is essentially north south so inland heats up in the morning sucking air in from the cooler ocean. This movement of air always turns 45 degrees (Coriolis effect) So we get consistent SW winds from about 1PM on till about 9PM. This start time and strength depends on the prevailing pressure systems of course so a natural west wind will bring early sea breeze while a natural easterly will bring later gently sea breeze. (and hot weather)
Now also interesting is the way at night the land gets cooler than the ocean so we get a similar effect but much gentler of a land breeze that also tends to turn left so coming as a NE night breeze. Again aided or contradicted by pressure systems.
As said not so pronounced in UK due to less land heating. But here it makes sailing almost boring with consistent 18k winds every afternoon. Good luck with the voyage to the OP olewill
 
I can remember so years ago racing into the River Medway under spinnaker, but ahead were other yachts heading towards us under spinnakers. However between us was a hole in the wind, once crossed we all ended up on the wind. This is an extreme example of the natural breeze being cancelled by the sea breeze.
 
Sea breezes are also dependent on geography, with them not being particularly apparent in some places and regular as clockwork in others. Over here in the River Blackwater, on sunny days the SE sea breeze will kick in and get up to F4-5, when I lived in Cornwall, the more apparent piece was the land breeze that cropped up in the evening...
 
I'm not sure that I fully understand the article, illustrations would certainly help.

Imagine being on the south coast on a hot summers day (pure fantasy, of course). A sea breeze requires an off shore gradient wind, say northerly. During the late morning the air over the land warns, expands and rises. It is pushed out to sea helped by the gradient wind. Wind from the sea will now move north towards the shore to take the place of that rising. Further out to sea, the hot air will cool and fall, this creates the cycle.

As the southerly sea breeze develops, later in the afternoon, it will veer and blow more south westerly along the shoreline (Coriolis). This would put wind on the beam, later abaft the beam of a yacht sailing towards the east, or anti-clockwise along the coastline.
 
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yachtmilos said:
In an article I read online the following was written about sea breezes and a trip round Britain:

'When the sun heats the air above the land, it causes another set of atmospheric quirks, the most obvious being sea breezes that weaken or reverse the offshore winds. In many places the resulting winds veer during the day, tending to blow with the coast on their left, and the sea breeze effect can also influence a light onshore wind by increasing its strength and inducing a similar veer. This means that in fine weather the winds near the coast will often display a bias towards blowing anticlockwise around the land.'

Can anyone help to unpack this please? I understand the basics of a sea breeze, but not the veering bit i.e why this happens?
Also, in my mind veering means to turn to the right, so wouldn't this mean creating a headwind for going anti-clockwise? Can someone please explain how the sea breezes aid an anti-clockwise passage? And is it true that there is an anti-clockwise bias? Later in the article it says this:

'Our experience suggests the anticlockwise bias of sea breezes will make a difference for nearly half the trip'

...which indicates to me that there is more than half the trip that is not helped by the bias?

Clearly I am very confused. Any help, explained simply, would be much appreciated.
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Wind converges when it passes from coast onto sea & diverges when it passes from sea onto land.
If sailing up English Channel, wind near french coast, can often be much stronger than the wind near our south coast because of this effect.
 
yachtmilos said:
'Our experience suggests the anticlockwise bias of sea breezes will make a difference for nearly half the trip'

.
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My experience of 2 single handed round Uk trips is that most of the time the wind either does not blow or blows too hard. When it is not doing that it comes from the direction in which one wants to go whether you want to go clockwise or anticlockwise.
Just take loads of fuel
 
If you want to learn about sea breezes, and lots of other stuff too, sign up for one of Simon Keeling's courses, as I have attended today. Really interesting and very informative. Good fun too!
 
Very localised - especially if in an area like the Bristol Channel with land mass to north - S and East. Ilfracombe on a clear hot summer day will build up a SW my mid afternoon. If the main forecast was East 3-4 - by 20pm its flat calm. Had that day after day. If from SW then by evening its whipping up 5-6. What its doing on the Welsh coast however could be quite the opposite !
 
Watch the sky on a day when there's a lot of cumulus cloud (caused by thermals). A sea breeze front will kill thermic activity near the coast but can actually boost it where the cold air from the sea meets the warmer air - the line will be very clear and the strength of the sea breeze effect (both wind strength and to a lesser extent direction) will largely depend on the amount of thermal activity. The sea breeze effect causes a fairly predictable wind change but whether or not it helps you depends entirely on where you're going. What you can do is try and plan your passage so that any passage uses that wind change to your best advantage.

There's a really simple video below but a couple of points about it - first off a sea breeze front can and often does happen a lot earlier than the evening - certainly during the afternoon and it's not unknown to get them before midday in places where the air unstable and the temperature difference between night and day very marked. Second thing is that the wind doesn't always flow straight from sea to land or land to sea. The sea breeze effect will change the direction of any exactly airflow but that basic airflow according to Buy's Ballot's law will still be happening. The actual wind will be a result of the two airflows.

One other point - there's plenty of other things that happen to affect the wind - katabic winds for example can be very strong in the Med (the Bora is Katabatic).


 
We were sailing up the Suffolk coast in a Northerly direction on a port tack when I noticed that a boat some way further out to sea was on a starboard tack. I couldn't understand this but then the W breeze that we had been enjoying slackened and completely disappeared and suddenly an E breeze sprang up. Obviously this was the sea breeze which the other boat had been using which, preceded by a region of calm had then reached us. I had never thought before about exactly how the sea breeze developed and supplanted or combined with the normal wind. This was, of course, a special case where the normal wind and the sea breeze were in opposite directions and the latter overwhelmed the former.
 
yachtmilos said:
'Our experience suggests the anticlockwise bias of sea breezes will make a difference for nearly half the trip'

...which indicates to me that there is more than half the trip that is not helped by the bias?
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Sea breezes are much less common in Scotland than on the south coast of England. It's the sun heating the land bit where the difficulty lies.
 
yachtmilos said:
In an article I read online the following was written about sea breezes and a trip round Britain:

'When the sun heats the air above the land, it causes another set of atmospheric quirks, the most obvious being sea breezes that weaken or reverse the offshore winds. In many places the resulting winds veer during the day, tending to blow with the coast on their left, and the sea breeze effect can also influence a light onshore wind by increasing its strength and inducing a similar veer. This means that in fine weather the winds near the coast will often display a bias towards blowing anticlockwise around the land.'


Also, in my mind veering means to turn to the right,

It might be a little easier to understand if you will accept that veer simply means turning as does ,for example , sheer.
Click to expand...
 
25931 said:
yachtmilos said:
In an article I read online the following was written about sea breezes and a trip round Britain:

'When the sun heats the air above the land, it causes another set of atmospheric quirks, the most obvious being sea breezes that weaken or reverse the offshore winds. In many places the resulting winds veer during the day, tending to blow with the coast on their left, and the sea breeze effect can also influence a light onshore wind by increasing its strength and inducing a similar veer. This means that in fine weather the winds near the coast will often display a bias towards blowing anticlockwise around the land.'


Also, in my mind veering means to turn to the right,

It might be a little easier to understand if you will accept that veer simply means turning as does ,for example , sheer.
Click to expand...

My reading of what you have quoted is that veer is being used to say turn to the right. i.e. wind starts off blowing directly onshore. It veers and blows with the coast on its left.
Click to expand...
 
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