We should build wind turbines underground!

dj jarvis

TeddyTedson wrote: »

Did you know a 11 KW Turbine costs about 80,000euro. That would power one and a bit electric showers!

JESUS - thats some shower ya have teddy :eek: - how feckin big are ya ??

but seriously - here ya go

Toaster : 800-1500W
Microwave : 600-1500W
Dishwasher : 1200-1500W
Washing Machine : 500W
Vacuum Cleaner : 200-700W
Iron : 1000W
Electric Mower : 1500W
Clothes dryer : 4000W
Ceiling Fan : 10-50W
Table Fan : 10-25W
Electric Blanket : 200W
Hair Blow dryer : 1000W
Electric Shaver : 15W
Laptop Computer : 20-50W
Desktop Computer : 80-150W
TV (19" colour) : 70W
Clock radio : 1W
9" disc sander : 1200W
3" belt sander : 1000W
Fridge / Freezer : 500W
25" colour TV : 150W
Electric Kettle : 2000W
Power Shower : 240W

TeddyTedson

dj jarvis wrote: »

JESUS - thats some shower ya have teddy :eek: - how feckin big are ya ??

but seriously - here ya go

Toaster : 800-1500W
Microwave : 600-1500W
Dishwasher : 1200-1500W
Washing Machine : 500W
Vacuum Cleaner : 200-700W
Iron : 1000W
Electric Mower : 1500W
Clothes dryer : 4000W
Ceiling Fan : 10-50W
Table Fan : 10-25W
Electric Blanket : 200W
Hair Blow dryer : 1000W
Electric Shaver : 15W
Laptop Computer : 20-50W
Desktop Computer : 80-150W
TV (19" colour) : 70W
Clock radio : 1W
9" disc sander : 1200W
3" belt sander : 1000W
Fridge / Freezer : 500W
25" colour TV : 150W
Electric Kettle : 2000W
Power Shower : 240W

I'm actually not joking. That's a power shower. Most electric showers today are 9.5 kW.

kirving

Power shower is one with a motor, my electric shower is like 9kW. Admittedly it's not on maximum the entire time, but they use a savage amount of power.

There are a number of other big problems with say a telescopic base. The first is strength, there are serious forces on a wind turbine, which cause a large bending moment right down the tower. This is part of the reason they are wider at the bottom.

If we were to have a telescopic tower, it would have to be considerably wider at the bottom to allow the other sections to fit inside it. On a quick calculation I'm just after doing on Microsoft calculator, you'd need a pressure of 50 bar, in a 1M diameter tube to lift a 350 Tonne turbine. Obviously these are inversely proportional to one another, but any thinner of a hydraulic ram, and you're getting into pressures which the Shell2Sea protestors would say will kill everyone in a 50km radius if damaged.

That's about 70 tonnes of fluid per turbine, which has to be kept somewhere too.
Then you're onto collapsible blades and all that lark.

What may work is lying them flat, and then winching them upright, electrically, but that has serious problems of its own. Not worth it I don't think. I quite like them too.

hoochis

dj jarvis wrote: »

think before you post - it DOES NOT HAVE TO BE A COMPLETE SOLID STRUCTURE

christ - compressed air or oil can push a telescopic turbine into the air , and keep it there until it needs to come down

its far from impossible - everyone thought the mars mission today was toast

well think again - we have the technology to DO ANYTHING - just maybe not the cash

and with that attitude we will still be burning polish coal and using British nuke stations - and pumping saudi oil

pathetic

Im all for wind turbines but who is going to pay for these hair brained ideas? Do you realise how big these turbines actually are? A telescopic turbine would never return the cost of development. Its not a pathetic attitude. Its a realistic attitude!

The MiniVan

dj jarvis wrote: »

think before you post - it DOES NOT HAVE TO BE A COMPLETE SOLID STRUCTURE

christ - compressed air or oil can push a telescopic turbine into the air , and keep it there until it needs to come down

its far from impossible - everyone thought the mars mission today was toast

well think again - we have the technology to DO ANYTHING - just maybe not the cash

and with that attitude we will still be burning polish coal and using British nuke stations - and pumping saudi oil

pathetic

Do you know for fact that the tower does not have to be a solid structure?Can you give any examples of towers on turbines that operate like this anywhere on the planet?Thanks.

dj jarvis

Kevin Irving wrote: »

Power shower is one with a motor, my electric shower is like 9kW. Admittedly it's not on maximum the entire time, but they use a savage amount of power.

granted

but arklow had 6 turbines ( at sea ) and they produce 3600000 watts of power , so that's 600000 watts per turbine , these were built in 2005/6 , so have returned the original cost and more

its a long play deal really

abouttobebanned

Confab wrote: »

Wind turbines are all over Europe and don't piss anybody off. Only in Ireland would we scorn free energy because some fucker wants an uninterrupted view of the mountains where their grandad was surprise butt-sexed by the Black & Tans.

This is genuine comedy. I tip my hat to you sir.

Heroditas

dj jarvis wrote: »

think before you post - it DOES NOT HAVE TO BE A COMPLETE SOLID STRUCTURE

It does need to be solid.
We're talking about tonnes of material stuck 100m up in the air with blades of 70m length attached to the gearing.

dj jarvis

Kevin Irving wrote: »

Power shower is one with a motor, my electric shower is like 9kW. Admittedly it's not on maximum the entire time, but they use a savage amount of power.

There are a number of other big problems with say a telescopic base. The first is strength, there are serious forces on a wind turbine, which cause a large bending moment right down the tower. This is part of the reason they are wider at the bottom.

If we were to have a telescopic tower, it would have to be considerably wider at the bottom to allow the other sections to fit inside it. On a quick calculation I'm just after doing on Microsoft calculator, you'd need a pressure of 50 bar, in a 1M diameter tube to lift a 350 Tonne turbine. Obviously these are inversely proportional to one another, but any thinner of a hydraulic ram, and you're getting into pressures which the Shell2Sea protestors would say will kill everyone in a 50km radius if damaged.

That's about 70 tonnes of fluid per turbine, which has to be kept somewhere too.
Then you're onto collapsible blades and all that lark.

What may work is lying them flat, and then winching them upright, electrically, but that has serious problems of its own. Not worth it I don't think. I quite like them too.

Again , its could be done but should it ? well that is a different question

my point was that some of the best ideas are shot down by na sayers who dont have a clue , then it turns out to change every body's life in some way ,
the OP asked could it be done in some way - and yes it could be done - would it be cost to much ? probably , but could it be done - well yes

i think some of the respondents here are forgetting that lots of new TOWER BLOCKS in quake prone city's are on hydro rams that MOVE AND STABILIZE a building in a quake

so the can lift and move a sky scraper but not a wind turbine of some description ?
im sure it can be done , has it been done ? i don't know
should the question be asked can it be done ? yes
or as a species we will never move on

the question that the OP asked is valid and more like it should be asked

the real problem in this debate is the NIMBY question , which is for the greater good , 20 peoples view and quality of life or 200,000 peoples ?

answer this , and sunken turbines with hydraulics will never need to be built

Donnielighto

The MiniVan wrote: »

OK do you have any idea how big those turbines are?I know they might look quite small far away up on hills from you but they are in fact MASSIVE!Try and think of the Father Ted episode where Ted is teaching Dougal about near and far away:D

Now imagine the cost of having to dig down over 20 meters for EACH turbine and the enormus cost and amount of electricity (this is what the turbines are suppose to be generating in the first place,kinda counter productive now aint ya:D) to rise these huge,several ton machines out of the ground everyday!

Sorry dude I dont think your idea is gonna catch on:)

The electricity to lift hem could be quite small if a decent pulley system with weights was involved

dj jarvis

The MiniVan wrote: »

Do you know for fact that the tower does not have to be a solid structure?Can you give any examples of towers on turbines that operate like this anywhere on the planet?Thanks.

is a car Ariel not a solid structure , or a hydroram that can push thousands of ton's not also lift something a mere 70 tons ?

not saying i have the plans for this in my back pocket - but it could be done
its used in other applications - so why not this?

dj jarvis

hoochis wrote: »

Im all for wind turbines but who is going to pay for these hair brained ideas? Do you realise how big these turbines actually are? A telescopic turbine would never return the cost of development. Its not a pathetic attitude. Its a realistic attitude!

LOL the pathetic was for us importing from said country's , not your attitude

TOUCHY :eek:

pljudge321

dj jarvis wrote: »

they could be placed if not under ground then close to it - has no one come across telescopic's before ? high pressure hydraulics ?
also the windier areas dont need massively large ones , so the calculations done earlier on how much it would cost to " raise " the turbines is far from correct and a red herring ( does your face look like this :eek: ? )

If you had actually understood what I had written you would have seen that I pointed out that the energy needed was a trivial next to how much the turbine would generate.

That doesn't stop it from being a stupid idea however. Think of how much more engineering and excavation work would be needed, the added maintenance problems and the fact that you wouldn't be able to use the land for agriculture like is currently done.

Jesus wept indeed.

hoochis

dj jarvis wrote: »

granted

but arklow had 6 turbines ( at sea ) and they produce 3600000 watts of power , so that's 600000 watts per turbine , these were built in 2005/6 , so have returned the original cost and more

its a long play deal really

Do you know anything about turbines? 600000 watts per turbine? Where did you pluck that figure from?

The MiniVan

Heroditas wrote: »

It does need to be solid.
We're talking about tonnes of material stuck 100m up in the air with blades of 70m length attached to the gearing.

Exactly.The idea that you could just pop a huge structure like a wind turbine up in a telescope way is a bit off the head.
Im all for new bright ideas but that aint one of them dj.Think of the massive strains and forces on that structure from the wind and trying to keep those massive blades in place.

Even if you could in some amazing way make the tower like a telescope what are you gonna do with the blades baring in mind that some of the them could be over 70 meters long?Where are they gonna go when your telescope tower is in its retracted position?Are you gonna make them like a telescope too?
Now its just getting silly:)

PseudoFamous

dj jarvis wrote: »

granted

but arklow had 6 turbines ( at sea ) and they produce 3600000 watts of power , so that's 600000 watts per turbine , these were built in 2005/6 , so have returned the original cost and more

its a long play deal really

Just some quick corrections:

There are 7 turbines on the offshore farm, and they originally planned to build 200. The company building them are looking for government handouts to pay for the other 193.

The turbines (GE) produce 3.6MW each (i.e., 3,600,000W at full generation capacity per turbine, roughly 25MW total)

Of course, General Electric no longer make the 3.6MW turbines, so to finish the plant, they'd have to either switch to 4MW or 2.5MW (Which are primarily land-based turbines, perhaps unsuitable for offshore conditions), which would result in either a greater cost or larger number of turbines to generate the same amount of power.

magicbastarder

Colmustard wrote: »

We shouldn't build wind turbines these are the white elephants of the day, they have not succeeded in getting one gram of CO2 out of the atmosphere what they have succeeded in doing is employ about 200 thousand danes and germans who has pushed them into the EU energy charter.


We are been had.
From Des Spiegel

http://www.spiegel.de/international/business/0,1518,606763,00.html

that article points the finger at the emissions trading scheme, not wind energy itself.

hoochis

PseudoFamous wrote: »

Just some quick corrections:

There are 7 turbines on the offshore farm, and they originally planned to build 200. The company building them are looking for government handouts to pay for the other 193.

The turbines (GE) produce 3.6MW each (i.e., 3,600,000W at full generation capacity per turbine, roughly 25MW total)

Of course, General Electric no longer make the 3.6MW turbines, so to finish the plant, they'd have to either switch to 4MW or 2.5MW (Which are primarily land-based turbines, perhaps unsuitable for offshore conditions), which would result in either a greater cost or larger number of turbines to generate the same amount of power.

Or they could switch to vestas who are now producing 7mw offshore turbines.

crazy cabbage

Look. Wind power is a brillent idea but the form that we are currently looking at is not great all in all as people have alread pointed out


Look at this video. It purposes a 'kite turbine' or sorts. Is a brillent idea. We need more ideas like this. Look at around 3.40 if you dont wont to watch it all for quick idea of how it works

This gets rid of the problem of 'ruining the look of the landscape' and we dont need to 'put them underground'. As the video suggests we can potentally put these thousands of feet in the sky with a 'rope' essently connecting it to the ground.

Edit: yea i know that there is lots of challenges but it is ideas like this that will sove our problems. We need more ideas like these

dj jarvis

hoochis wrote: »

Do you know anything about turbines? 600000 watts per turbine? Where did you pluck that figure from?

da net

arklow has 7 producing 3.6 mega watts each, or 3600 kilowatts

, consists of seven GE 3.6-megawatt generators. They were installed by the Danish offshore wind farms services provider A2SEA.[1] Power cables were laid by Five Oceans Services.[2] All of the turbines have a height of 73.5 metres (241 ft) and height to top of blade of 124 metres (407 ft). The blade length is 50.5 metres (166 ft) and each turbine has three blades

so.... 3.6 mega watts or 3600000 watts per turbine- so in fact i UNDER estimated EACH turbine by a large margin - thanks for pointing that out

you can do the calculation here http://www.rapidtables.com/electric/watt.htm#conversion_calculator

anything else you would like to know, but are to lazy to Google yourself ?

TheIrishGrover

delad wrote: »

.............But what if the turbines were stored underground and only came up above ground at night time. This would annoy no one since they wouldnt be able to see them in the dark. They could also be brought above ground at other select times during the day, like during times of strong or gale force winds.......

Someone's been watching too much Thunderbirds

dj jarvis

The MiniVan wrote: »

Exactly.The idea that you could just pop a huge structure like a wind turbine up in a telescope way is a bit off the head.
Im all for new bright ideas but that aint one of them dj.Think of the massive strains and forces on that structure from the wind and trying to keep those massive blades in place.

Even if you could in some amazing way make the tower like a telescope what are you gonna do with the blades baring in mind that some of the them could be over 70 meters long?Where are they gonna go when your telescope tower is in its retracted position?Are you gonna make them like a telescope too?
Now its just getting silly:)

no , they support whole sky scrapers on hydraulics and move them today , now , as we speak
so not as pie in the sky as we think

dublin has the east link bridge - it is raised by hydraulics , it weighs more than a turbine i would imagine , now the lights don't go dim in Dublin when it is used , it did not break the bank and the technology has been used for nearly a 100 years - it also did not break the bank to install - maintain or run

im not saying AT ALL its commercially viable - but IT COULD BE DONE
and off the wall ideas have a habit of changing the world - this might not be one but you never know until the idea is produced

keep them coming OP

Heroditas

dj jarvis wrote: »

so.... 3.6 mega watts or 3600000 watts per turbine- so in fact i UNDER estimated EACH turbine by a large margin - thanks for pointing that out

you can do the calculation here http://www.rapidtables.com/electric/watt.htm#conversion_calculator

anything else you would like to know, but are to lazy to Google yourself ?

You need to take the capacity factor into account.
They'll rarely, if ever, run at 3.6MW

Yakult

Just build them out in the sea ffs.

LETHAL LADY

Has anybody harnessed the power of the male first thing in the morning fart?

OMARS_COMING_

Turn Ireland into a giant ant

theg81der

PseudoFamous wrote: »

Of course, General Electric no longer make the 3.6MW turbines, so to finish the plant, they'd have to either switch to 4MW or 2.5MW (Which are primarily land-based turbines, perhaps unsuitable for offshore conditions), which would result in either a greater cost or larger number of turbines to generate the same amount of power.

Nothing to stop you going to someone else like Siemens then thats a nule point, lots of other companies producing off shore suitable turbine.

theg81der

hoochis wrote: »

Or they could switch to vestas who are now producing 7mw offshore turbines.

There not even made yet its a prototype = bad plan!

dj jarvis

Heroditas wrote: »

You need to take the capacity factor into account.
They'll rarely, if ever, run at 3.6MW

i know - but that was not the question that was asked

it was asked where i got my figure of 60000 from , the person asking the question obviously did not know the difference between mega watts and watts
as it turned out i was under estimating the watts by a large margin -

so even sweeter for me

hoochis

dj jarvis wrote: »

da net

arklow has 7 producing 3.6 mega watts each, or 3600 kilowatts

, consists of seven GE 3.6-megawatt generators. They were installed by the Danish offshore wind farms services provider A2SEA.[1] Power cables were laid by Five Oceans Services.[2] All of the turbines have a height of 73.5 metres (241 ft) and height to top of blade of 124 metres (407 ft). The blade length is 50.5 metres (166 ft) and each turbine has three blades

so.... 3.6 mega watts or 3600000 watts per turbine- so in fact i UNDER estimated EACH turbine by a large margin - thanks for pointing that out

you can do the calculation here http://www.rapidtables.com/electric/watt.htm#conversion_calculator

anything else you would like to know, but are to lazy to Google yourself ?

I dont need a conversion calculator to convert from watts to megawatts. Its really pretty straightforward. The reason I asked where you got that figure from was because I knew it was completely wrong at first glance. Now that you had to research the figures that you quoted, it will stick better in your mind. Im really only helping you out

hoochis

theg81der wrote: »

There not even made yet its a prototype = bad plan!

A friend of mine working with vestas told me a few months that they would start producing them this Autumn. Probably be a couple of years before any of them are up and running though.

dj jarvis

so as usual in AH the point you are trying to make is ignored or misunderstood

OP made a suggestion that was shot down before it was even properly considered IMO,

i mentioned hydraulics and telescopic's among other things a SUGGESTIONS on how you could tackle this issue ( lowering and raising turbines )

i not once said that it should be done, or considered in a real world scenario
BUT i did, and do say that in the world of engineering today it would be relatively easy to do this.

as i have said before ( people on AH have a great habit of picking and choosing what they want to quote ) the technology is in use in quake zones to stabilize sky scrapers - bridges - oil rigs to mention a few , and these all weight CONSIDERABLY more than a turbine

FFS i have a hydraulic trolley jack in my garage with a 10.5 ton weight capacity for lifting vans and small trucks and its hand operated
so the use of this method to lift vast weights easily is in everyday use

should it be done? probably not
could it be done? absolutely - without a doubt

if anyone reading this is in uni - go ask your engineering master could it be done - i would wager he could give you examples of where it is being used today - in Ireland

dj jarvis

hoochis wrote: »

I dont need a conversion calculator to convert from watts to megawatts. Its really pretty straightforward. The reason I asked where you got that figure from was because I knew it was completely wrong at first glance. Now that you had to research the figures that you quoted, it will stick better in your mind. Im really only helping you out

yea yea - i can here the back peddling from here
as i explained to you earlier, the pathetic comment you pick up wrong and was not intended - so no need to jump on every post i am making

im a lover not a fighter

hoochis

dj jarvis wrote: »

i know - but that was not the question that was asked

it was asked where i got my figure of 60000 from , the person asking the question obviously did not know the difference between mega watts and watts
as it turned out i was under estimating the watts by a large margin -

so even sweeter for me

I dont think you do know. Anyone that quotes a figure of 0.6mw for an offshore turbine really does not have a clue what they are talking about. That is why I brought your mistake to your attention! Looks like you are the one back peddling!

dj jarvis

hoochis wrote: »

I dont think you do know. Anyone that quotes a figure of 0.6mw for an offshore turbine really does not have a clue what they are talking about. That is why I brought your mistake to your attention!

see !!! jesus kid relax will ya :eek:

hoochis

dj jarvis wrote: »

see !!! jesus kid relax will ya :eek:

Im very relaxed! Im not a kid! Im not fighting with you nor do I love you! Im just disagreeing with you!

A Primal Nut

How about we start metering the amount of power from the grid which wind turbines take in so we compare with the amount it produces? According to the maths we'll see they aren't a net producer here in Ireland.

The MiniVan

dj jarvis wrote: »

no , they support whole sky scrapers on hydraulics and move them today , now , as we speak
so not as pie in the sky as we think

dublin has the east link bridge - it is raised by hydraulics , it weighs more than a turbine i would imagine , now the lights don't go dim in Dublin when it is used , it did not break the bank and the technology has been used for nearly a 100 years - it also did not break the bank to install - maintain or run

im not saying AT ALL its commercially viable - but IT COULD BE DONE
and off the wall ideas have a habit of changing the world - this might not be one but you never know until the idea is produced

keep them coming OP

You didnt tell us what you are gonna do with the 70 meter blades when your turbine has retracted?

But listen I wish you all the best with your telescope wind turbine I would advise against investing any money into developing the idea and in the words of Duncan Bannatyne:''I'm out'':)

pljudge321

A Primal Nut wrote: »

How about we start metering the amount of power from the grid which wind turbines take in so we compare with the amount it produces? According to the maths we'll see they aren't a net producer here in Ireland.

Now you're into crazy conspiracy theory territory. Wind generation produced about 4400 GWh last year which is about 16% of the total electricity generation for the year.

dj jarvis

The MiniVan wrote: »

You didnt tell us what you are gonna do with the 70 meter blades when your turbine has retracted?

But listen I wish you all the best with your telescope wind turbine I would advise against investing any money into developing the idea and in the words of Duncan Bannatyne:''I'm out'':)

dont remember asking for cash - yet !!

as for retractable blades , i seem to remember helicopters having a system of storage for the blades when going below deck in carriers or in for maintenance,
they can be stacked on top of each other along the rotor arm , so would only be as wide as one blade , so using this you do the same with the body of the turbine mount ( ie 12/6 on a clock if you understand what i mean )

im SURE this problem has been well solved before , not that i can think how off the top of my head - but now i will try think of a solution

this is my point about the OP's suggestion - mad idea it might be , but while trying to figure out could it be done, you solve many other useful things along the way.

now back to the cash - how does 25% of my new company FOLD AND BLOW turbines IRL for 250,000 sound to ya ?
PM with the drop address for the draft :eek:

edit ** ok , looks like my idea is not so mad - some one has done it ( test plant only - but done ) bang goes my business **
http://www.care2.com/causes/wind-turbine-blades-with-telescopic-arms-catching-the-breeze.html

Zab

I thought you were taking the piss when you first started posting in this thread dj. It was only after a few posts that I realized you were actually being serious.

The fact that this thing only generates electricity at night makes it a non-starter to begin with.

Heroditas

A Primal Nut wrote: »

How about we start metering the amount of power from the grid which wind turbines take in so we compare with the amount it produces? According to the maths we'll see they aren't a net producer here in Ireland.

Wind farms already are metered.
They use only a small amount of electricity - a paltry fraction of what they produce.

dj jarvis

Zab wrote: »

I thought you were taking the piss when you first started posting in this thread dj. It was only after a few posts that I realized you were actually being serious.

The fact that this thing only generates electricity at night makes it a non-starter to begin with.

na , the at night thing is pointless , and will or should it ever be done , well prob not

my point is this - could it be physically be done , in a engineering view point , i was arguing it could be done
not that it should be
2 totally different things

and i NEVER take the piss when on AH - im deadly serious :rolleyes:

Choochtown

Spending money on developing wind farms etc. is a waste.

They will never provide enough energy for us when fossil fuels are gone.

We should be pumping all our money, research etc. into nuclear fusion.

kowloon

D1stant wrote: »

Over large land masses yes. West coast of Ireland, dont think there is any difference

The Kerryman travelled there at night so his spacecraft would not burn up....

I thought it was in Winter when it wasn't so warm.

PC CDROM

CSU wrote: »

is it not windier at daytime?

Shoots self in head.

I found my breaking point. No offence. Seriously.

dj jarvis

PC CDROM wrote: »

Shoots self in head.

I found my breaking point. No offence. Seriously.

Capt'n Midnight

instead of hiding them underground we just need to make them taller

1km tall with 1km blade diameter. that way you'll never get within 500m of them ( make them even taller if that's too close )

with all the rain and mist we'll hardly ever see them and you won't hear them because they won't be going wooop-wooop-wooop

pljudge321

Capt'n Midnight wrote: »

instead of hiding them underground we just need to make them taller

1km tall with 1km blade diameter. that way you'll never get within 500m of them ( make them even taller if that's too close )

with all the rain and mist we'll hardly ever see them and you won't hear them because they won't be going wooop-wooop-wooop

You'd probably get the odd bang from the tip breaking the sound barrier :pac:

CSU

PC CDROM wrote: »

Shoots self in head.

I found my breaking point. No offence. Seriously.

...none taken, but FTR it is windier during daylight hours.:rolleyes:

chicagotribune.com wrote:

Dear Tom,

Why is daytime windier than night? Gusty daytime winds calmed as soon as night approached the other day--something I've noticed many times. Next morning at sunrise, the gusty winds were back.



Scott Hosford, Iowa City, Iowa

Dear Scott,

Much of the tendency for winds to blow with more force in daytime is driven by sunlight and solar heating. The sun unevenly heats earths surface which, in turn, imparts uneven warmth to the air immediately above. A plowed corn field heats far more aggressively in sunlight than does a highly reflective snow covered field nearby. The resulting variation in air temperature produces pressure variations--i.e. lower pressure over the warmer cornfield and higher pressure above the snow. A wind is natures way of attempting to balance these imbalances.

Sun-induced heating disappears with the onset of darkness, and winds often fade. But, there's another factor at work. Nighttime cooling often sets up temperature inversions--a condition in which colder, denser air collects near the ground, while milder temperatures prevail above. Such inversions effectively shunt large-scale, organized winds away from the surface, forcing organized winds over the pool of cool air.

---

Tom Skilling is chief meteorologist at WGN-TV. His weather forecasts can be seen Monday through Friday on WGN News at noon and 9 p.m.

Send your questions to:

ASK TOM WHY, 2501 Bradley Place, Chicago, Il. 60618

e-mail: asktomwhy@tribune.com