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Ask Slashdot: Large-Scale DIY Outdoor Cooling of Cairo's Tahrir Square?
ClimateHacker writes "The struggle for freedom is still ongoing in Egypt and one of the many challenges that face the demonstrators in Tahrir Square is the sweltering heat. Skies are mostly clear and temperatures can reach up to 44 degrees Celsius (111 F) with hardly any shade. The risk of life-threatening heat stroke is quite real. I ask clever Slashdotters out there for novel DIY passive and active ambient cooling techniques. Perhaps some ideas could be a model for saving energy on cooling elsewhere."
Making shade is the obvious solution. Anything from portable gazebos to improvised Berber tents to poles and shade-cloth. Shade is going to be more efficient than anything else at keeping people cooler.
If water can be spared, a fine mist of water in one part of the square would let people who have gotten too hot cool themselves down.
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Pheonix Az & several other cities use tall evaporative towers to cool plazas -- pump water to the top & let it cascade down over tera-cotta tiles. The evaporation drops the air temperature and the cooler air combined with the dropping water forces the cooler air out the bottom of the tower.
Get a tarp.
Get some poles.
Profit.
Which is what I saw the protesters doing months ago. You get some shade, drink lots of water, and avoid heavy exertion. Basic hot weather protocol, which is all those protesters are going to bother to do. This isn't fucking rocket science, but this is one of the most retarded Ask Slashdots I have ever read.
Why the fuck does your Western arse think it is smarter then the people who have lived in those climates for at least the past thousand years?
========
CINC, 4th Penguin Legion
Water will help as well... drink it plenty.
Questions raise, answers kill. Raise questions to stay alive.
Wear long, loose white clothes. Place a towel or something similar on/around your head, sort of like a hood.
I've heard that they do this with great success in some countries.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
The only cool and innovative thing I think would work is setting up a piezoelectric floor to power some mist fans. Otherwise, just get out of the farking sun and put up some shade.
How about each person bringing in a small circular tub (1ft dia) that has 5ltrs of water and keeping it near to him/her.
Water evaporating from clothes. Arrange for fire service to spray people with water from the trucks. This is quite common in outdoor festivals - the car moving very slowly through the crowd, and firemen pouring a mist of water over the crowd. This suffices for a hour or so, can be repeated as needed. Also, if anyone faints, or feels otherwise ill, they can be handed over to the fire truck to be taken out to a medical station..
Otherwise, if you can't get cars, just get a bottle of water for yourself and pour it over yourself from time to time.
45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
Scantily clad women with large fans (to fuel the fervor for women's rights, while cooling everyone off, of course.)
And be part of the solution, you lazy smelly hippies.
If you were blocking sigs, you wouldn't have to read this.
Have water run over a thin plate of some sort (glass is more aestethical pleasing) and have a stream of cold water run over it while your container or source of water is cooled. (your container before repumps the water fe.)
In these temperatures, place de device preferably in a enclosed improvised portable room (aka "tent").
The result should be a pleasing soothing sound of water, in cooled down high humidity where you can optionally get funky with a nice beer while you're protesting.
I think we can keep recursing like this until someone returns 1
Let's see... something that reflects heat, and has other possible benefits against an abusive government... hmmmm...
Have you considered a tinfoil hat?
with air conditioners!
A wet towel around the neck is an efficient way to stay cool. The evaporating water cools the towel and the adjacent arteries and veins going between the brain and torso. Bill
I have seen two layers of shade work very well. The first layer absorbs the sunlight and the second layer spaced apart beneath creates a draft between the two layers which isolates the people below from the upper hot shaded material. White is much better at reflecting heat, dark colours absorb heat. Fans or moving air is more practical than cooling. So two white sheets spaced 50cm apart would be best. Keep the sheets as high up as possible.
Obviously not a DIY solution - but I was wondering if a government wanting to do this on a large scale could actually use a solar updraft tower type design directly above the area that would suck hot air out and bring in a breeze and and (hopefully) cooler air from the surrounding vicinity. Bonus: you get power from it as well
http://en.wikipedia.org/wiki/Solar_updraft_tower
http://science.slashdot.org/story/01/12/10/0610203/Thermal-Solar-Plant-To-Be-Erected-In-Australia
Come live in Darwin, Australia where the temp gets as high as 40c with 100% humidity!!!.... Harden the f%$k up!! lol......
This sounds completely like a troll. First, the weather in Cairo is hot, but not 44 degrees C hot. Second, people do not hold prolonged protests in Tahrir nowadays. Third, protesting isn't supposed to be an easy activity. You're not guaranteed certain conditions like you're in a freaking office. Forth, any real protestor would worry about tear-gas and batons way more than they would about the heat.
And that's why the original question strikes me as stinking of colonialistic snobbery. OTOH, if some genius here can somehow, with only second- to third-hand knowledge of what kind of resources are really available and what conditions are really like over there, come up with a solution which will make their life easier, I'm all for it.
I'm not holding my breath.
simple : use misters .Water comes in , goes through nozzles to make tiny droplets , then the fan pushes the air and moisture.
These devices have been in use in large spaces in Florida for years.Keep a place cool ? Use a mister.
Even available as rentals 8)
FTB
Blame Israel for the heat as well. You'll feel much better immediately.
Spray a firehose upwards through something that will make a fine mist. Most will evaporate, sucking vast amounts of heat out of the air, which will flow downwards onto the crowd, along with the remaining chilled water. You want pressure rather than sheer volume.
Burlap/canvas tents can be cooled with a constant trickle over them in the same way.
Slightly less messy might be a series of hoses that carry chilled water from a tank out to modified hot-water-bottles strapped to people, and then away again, maybe even back to the tank to close the system. Rip a few fridges apart and put the cooling pipes in the tank. Run any waste water over the hotside pipes and then into the drains.
It's like CPU cooling, just on a larger scale: :-)
Jeremy Lee | Orinoco
I realize the initial request was for large scale cooling options but an affordable equivalent to synthetic cooling towels would help drastically. Draped over the neck, the towels take advantage of evaporative cooling.
/.ers can recommend an equivalent like say a damp cotton/polyester blend rag.
Sadly with the lack of foresight there's probably not enough time to organize sponsorship from one of the multiple companies competing for market dominance but I'm sure our resourceful
After consulting Google maps and images, I see the environment is roughly:
1) Flat terrain, near the Nile river
2) Mostly concrete
3) Standing-room only
So I would say the solution would mostly comprise
1) Shade,
2) Drinking lots of water, and
3) Air flow
Setting up awnings shouldn't be too difficult. It should be possible to filter, bottle and chill water on site. Procuring some large fans and some type of power supply should be possible as well.
"I assumed blithely that there were no elves out there in the darkness"
Why is the square a circle?
In addition to the above posts about reflecting away heat from above, may I suggest you wet down the pavement in advance.
This will reduce the heat coming from the hot pavement below which may otherwise reach dangerous temperatures.
Burn hydrocarbons. Lots of them.
Love,
The real "ClimateHacker."
A couple years ago I was at universal studios in August (a hot time to be in Florida) what they had was a kiosk of misting stations just some pipes pumping a fine mist of water to a group of 10 people at a time. For about a minute in those you feel better for about 15 minutes. But you could store a large tub of water and a gas pump and place these at key locations. After you are done you take it apart and pack it away.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Are you seriously trying to suggest DIY temperature cooling techniques to people who have been living in the desert for mileniums?
This is hilarious... Or else, really really condescendent, almost racist.
Ask the RAF to fly them over some British weather. We'd be happy to spare it, really!
I am TheRaven on Soylent News
A couple of years ago in Penang I took a tour of the botanical gardens. A short section of the tour took us through a stretch of native forest. The microclimate in the forest was much more comfortable than other areas. So break up the concrete and replace it with trees. I know this may not sound very feasible in the short term but it is the only way to beat the climate in the long term.
http://michaelsmith.id.au
It's a squared circle.
You have got to be kidding me. You seriously thing anyone on Slashdot has anything to teach the people of Egypt anything about how to stay cool in the heat, in a civilisation that has been running countless generations of agrarian workers out in the fields on the Nile delta for ten / twelve hour days for oooohh, over ('scuse me) FIVE THOUSAND (ahem) years and the millions of city dwellers who also make their livelihoods substantially outdoors? Either this is an epic troll or epically short of self-awareness.
slighly off-topic: two major cities - tel aviv and bangalore - cut down large numbers of trees in order to make room for more people. the immediate result was a rise of 10 Centigrade in bangalore (from 45C to 55C). in tel aviv's case, not only did the temperatures rise but also migrating birds no longer have a stop-over point half way along their route between the two hemispheres.
not that planting some saplings in a public place is going to help in the immediate short-term, i appreciate...
The most energy efficient way to cool people is to pour ice directly into them. Give each person an styrofoam cup of crushed ice to eat. The low temperature of the ice plus the heat of fusion will pull a lot of heat.
What does this story have to do with bitcoin? :)
I would strongly suggest the use of water-cannons. Not only would water-cannons control protestors but they would also keep them refreshed and cool during their protests!
Life is sleep. Death is a dream. Wake up.
As above, shade, water mist, & vegetation are options, however in the desert water is in short supply (that's why it's call desert, duh :))
Capture the wind as some house architecture in the region does.
Dig down several feet, there is ample cool water there, and, the temperature is MUCH cooler. Use windmill for power.
I'd suggest anything that can create shade, either making some space blanket awning (something like this perhaps) or try to get hold of cheap beach umbrellas.
The umbrellas can also be painted with slogans etc.
What you are looking for is called Radiant Barrier. If you feel like paying double or triple what the product is worth, visit your local big box hardware store. Otherwise hop on Ebay and buy a roll or two (usually 250' x 4') and use however is needed. Radiant barrier is strong - does not tear easily. Fully blocks all radiant heat.
2 layer shade.
Basically 2 suspended layers with an air gap in the middle.
Top layer blocks sun, but absorbs some heat, which is radiated in all directions, including downwards.
second layer easily blocks this radiated heat and air currents remove the heat from the layer of air inbetween.
I read about it when going to camp in Hungary (35C) and wanted to be able to sleep in my tent after sunrise.
Anyway, it works very well and apparently is used to great effect at the burning man festival (which is in the desert)
I used Ropes, Tarp, Poles and Pegs.
J.
water cannon
The following is what I have done at Burning Man festivals in the past.
1 - space blanket.... Yes a space blanket. they reflect 98% of Infrared and visible light. it makes a HUGE difference in the desert heat.
2 - water soaked white neck wrap. The evaporation effect of that wet cloth around my neck makes a GIANT difference in low humidity.
3 - water soaked white turban. Again.. Evaporation is your friend.
4 - white umbrella..... seeing a trend here? if you are in bright sun the best thing you can do is reflect as much of it's energy away from you as possible.
5 - wet clothing.. Again white, again wet.... isn't physics neat!
The biggest problem is pesky deserts dont have a constant supply of water. Someone needs to complain to the planet engineers about this oversight.
What I have discovered is that most people that live in those regions already know how to keep cool. It's the idiot Americans that cant understand why people don't die instantly when they dont have AC in their cars or homes that cant figure out how to stay cool outside.
Actually that was unfair. It's pretty much any Idiot that is lacking in education and lives in a 1st world society no mater what the country.
And yes, I am an American... Most of us really are pretty stupid when it comes to common sense and life skills.
Do not look at laser with remaining good eye.
Move demonstrations here. It is a cooler place, and given how things are going on in Egypt after Mubarak fall, I don't think the world will ever notice a difference.
Hmmm. They can't plant them directly... but they could bring in planter pots. Buckets of soil. Six guys to a tree.
We'd want to fill the square with as many as possible, using the least footprint. So, we need a locally available plant with a relatively small root ball, long stem, and large crown, with a high transpiration rate. This will cool the air and provide shade.
Botanists. We need botanists. They'll know.
Plus, the sudden greening of Tahrir square might be news-worthy by itself.
Jeremy Lee | Orinoco
What they do in Phoenix, Arizona to cool out door areas is have tall hollow cooling towers with openings at top and bottom (at ground level), and something akin to blankets hanging at the top kept wet.
Hot air comes in at the top of the tower, cools via evaporation of the water, and therefore becomes heavier/denser and falls down the inside of the tower then comes out of the openings at the bottom under it's own momentum.
I guess in a country where labor is super cheap you could have humans keeping the "blankets" wet rather than using a water feed, if that was a construction issue.
First you get twenty thousand eggs. Next, you make a big fucking omlette and then... oh wait...
Boredom is bliss.
Have the mosques and churches ask worshipers to bring bags of ice in when they come. Have protesters carry those to the square. Build cooling shelters from the ice and collect the melt water to filter and drink. Anyone who gets into medical trouble can get relief at the at one of the shelters. People who are not in trouble can get some relief from a cold drink.
What about water cannon? Doesn't the army have some of those?
At a constant 98.6 degrees Fahrenheit, a fine mist of the blood of the protesters would serve to keep people relatively cool without even counting evaporation.
Geodesic domes - with a possible side effect... Can't hurt to give it a try
For justice, we must go to Don Corleone
White, wet turbans. White wet clothing. You can use non-drinking water to soak the clothing. Even very warm water will help as it cools via evaporation.
Drink isotonic drinks at body temperature. If drinks are cold, the body produces more heat to cool the liquid down.
Don't forget minerals and vitamins. Minerals like regular table salt are important to keep the body going and the mood up, especially when people have been sweating a lot. Alcohol free beer, barley water and simular drinks are both isotonic and have the basic set of minerals. No soft-drinks or sugar. No alcohol. Rather drink less non-alcohol.
Full, lose clothing. Non-dark.
Important: If body-temperature is maxed out and people are at the edge of a sun-heat-stroke it is *always* better to be fully clothed. There is a reason why Bedus wear a Shesh. Also lose, long arms and lose long pant legs. It may feel warm for the layman, but body temperature eavens out at a high level with a full heat-shell rather than overheating in bare sunlight.
Consider Baggy pants or Hakamas for both ladies and men.
Hand-fans. You can build those easyly with wire and cloth if they are lacking. Build them large, take turns faning slowly.
Rescue blankets. Dirt cheap and super efficient at repelling heat. Use them to build sun-tarps and tents.
Hats are better than sun-glasses.
Sun & Heat Optimsed Head Garb in order of efficiency:
1 Shesh / Turban
2 Sombrero / Chinese Rice-Straw 'Dish' Hat / Cowboy Hat
3 Light-colored Longsleve wrapped as Shesh (instructions on the web)
4 Leginoaires Cap with neck-cover / Safari Helmet
Butter can help the skin if sun-lotion is lacking and the skin isn't burnt yet. Don't butter damaged skin! Use curd to cool and replenish burnt skin. (consult a doctor, medical disclaimer, blah blah ... y'know)
When cooling with cool-packs or ice apply the cool-packs at the lymph-nodes and don't let the sun at them. The human body has its own conditioning system and will spread the coolness to where it's needed the most from the lymph-nodes on out.
And last but not least: Good luck with your struggle. The thoughts of all of us are with you. And treat the egytian ladies fair! I'm looking forward to a time when the middle-east beauties can walk around free and are equal to men.
We suffer more in our imagination than in reality. - Seneca
Currently the humidity in Cairo is 89%. I doubt that the solutions used in one, very dry location in another country would work there.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
Most people here have the right idea. Make shade, give people water, and try swamp cooling (evaporative cooling) to take maximal advantage of the difference between wet bulb and dry bulb temperatures. I don't know the geography of Cairo so I'm unaware of the general humidity levels, but if Tahrir square is close to the river evaporative cooling might be difficult to use.
A secondary problem with evaporative cooling may be that your district water is already hot. This will diminish the effectiveness of your cooling tower. One commenter suggested allow the heat of the square to radiate out during the night; I'd suggest something analagous for a reservoir of water used in your cooling tower. Fill up and keep a reservoir of water in the square at night, allowing it to cool to ambient temperatures. Use this reserve for as long as possible during the day to get maximal cooling effectiveness with minimal humidity increase.
If you're dead-set on using a reservoir, it may also be a good idea to dig a hole for water storage in the ground, maybe 2m deep. At that depth, the temperature is close to maybe 15 degree C year-round in many parts of the world; regardless, it is still probably much colder than ambient air temperature.
It's been a decade or so since I've been down there but I remember the Downtown area next to the compass restaurant hotel having a misting system. Probably a horrible use of water but if it keeps people alive..
Also these guys might know what's up.
http://www.haciendarentals.com/cooling/
Beware of those who profit off the docile and persecute the unbelievers.
Tin-foil umbrella & wet clothes, with a little hope of wind, I'd say.
Here's my idea:
- Create two row of light colored cement blocks about a foot apart
- Place a steel or aluminium pole with a base into your bricked area and fill with sand or soil
- Plant a native grasses or shrub into the media you filled the bricked area with.
- On the top of the put a solar panel facing towards the sky and underneath the panel put a bank of cooling chips.
The solar panels will create shade,a wind block and reflect some of the light away. The grass or shrubbery will do the same will absorbing the heat. The brighter the day the more the panels will generate cool air. The cooling chip I was talking about would be something similar to those found in USB beverage coolers (see link below).
http://www.amazon.com/ZBANG-ZB006-USB-COOLER-WARMER/dp/B000WWUP3I
You say things that offend me and I can deal with it. Can you?
...the good intentions of someone who happens to live in North America or Western Europe and wants to help someone he sees struggling in another part of the world for colonialistic snobbery.
Telling people to mind their own business while someone else suffers, historically has not accomplished very much.
I'm in Taiwan right now. People here sometimes spread water all over the ground (though they do it in Japan a lot more). With enough people doing it, you can really cool the air in a local area just by watering the hot asphalt and letting it evaporate. Otherwise, people just stay in the shade. There are some misting tents, too. And, of course, big straw hats (though I don't think people in the middle east need help on dressing appropriately for hot weather, they seem to have had that covered for thousands of years).
If it's dry, and the temp is in the mid 30s, evaporative (swamp) cooling works pretty well. As the temperature starts to rise much above 40, it's not so effective. The temperature drop is only about 10C-15C, at the cost of greatly increasing the humidity, which actually makes things worse for the people, because humid air reduces the thermal cooling from sweating.
In the worst cases (at the shore in the gulf states/countries) the humidity can be high enough that the dewpoint/wet-bulb temperature is close to or above body temperature, in which case water in the atmosphere actually condenses on people, raising their temperature. (or worse, condensing in the lungs, forming a peculiar kind of pneumonia)
All that Middle East architecture to keep things cool by evaporation actually is more about "storing cold"... cool large massive things down at night, and then circulate air over them during the day. Large thick walls have a long thermal time constant, so, by the time the heat pulse from the daytime heat reaches the inside, it's actually night time, and the outside air is cool. So you rely on clever management of the ventilation patterns.
As others have pointed out.. shade and hydration is where it's at. hydration lets your body do the cooling (and 40-45C air temperatures, if not too humid, are easy for most people to tolerate)
That Tahrir Square is not square; it are round.
Is best and most cheaply done in almost all circumstances with shade and a fine mist of water.
And I saw exactly that in higher-end cafes in Morocco, Spain, and France during the summer.
Several ways:
Shade: As in wear a wide-brim hat. (Think sombrero.)
Evaporation: Get wet. Let the water evaporate. Evaporation is endothermic. You want the evaporation (cooling) to be as close to the skin as possible. Ideal spots are hands, feet, and neck. But arms, legs, chest, and back will work too.
Melting works well (also endothermic), but it doesn't last as long unless you insulate the material (such as ice). And it's harder to deal with. Keeping a hand in a styrofoam ice-bucket will let you function quite well in extreme heat. (Though watch out for your hand getting too cold, which causes discomfort. You might need to share a single ice-bucket amongst several people, each taking turns as they overheat.)
A wet towel is quite helpful with respect to evaporation.
A somewhat better solution lies in the crystals found in baby diapers. They are designed to absorb large quantities of water. Wrap them tightly in cloth, soak in water, and wear around your neck. It works! It's sold commercially in America. I've used it! (Though you will get a little sticky by the day's end.)
Breeze: Which leads back to Evaporation. A solar-cell and a fan do wonders. Or even just a battery and a fan.
In the US, you often see squirt bottles with a battery-operated fan attached.
Oh, and WEAR WHITE! Ideally white that is reflective above 800nm. The difference between wearing white and black is substantial!
These umbrellas (http://www.tenarafabric.com/medina.html) seem to be working quite well in Medina.
Stillsuits. The good desert models, not the shoddy ones sold in cities by museum Fremen.
1) Stop wearing all those clothes.
2) evaporative cooling for both people and in huge towers
If the people started wearing extremely light weight clothing - almost see through, that would help with evaporation from the skin. This is especially important for women.
I don't know that you can deploy enough cooling units for 20K people, but here in the states at large outdoor gatherings a firehose is often used to spray the crowd. 15 minutes later, it becomes muggy in that area and 15 minutes later all the water is gone - evaporated.
Personally i think we should ask the great Billy Mays, or fire millions of bullets straight into the air; that will create tons of shade...
all cool gardens in hot countries have a lot of trees to make shadow and even better, some running water on that shadow. No one yet out perfect this nature design on a open space.
one bit part of the problem is that the cities are more and more concrete, stone and roads, there is no green space, no shadow, no running water
of course, this is a very slow solution for the future children :)
for a short term solution, you need shadow, whatever material is good, but put at least 2 layers of it and some space between then (the "hotter the material gets, the bigger the space), so the first layer will get hot, but the air flow between the layers will keep the second layer cooler.
dont forget the indirect sunlight, if you get much indirect light, you are also getting indirect heat
Higuita
And that's why the original question strikes me as stinking of colonialistic snobbery.
Just because someone asks for help and thinks there might be a novel answer an expert might think of, even if it's a question it would have been nice to have an answer to any time in the last ten thousand years, doesn't mean we should call him a snob for asking. Ignorance or shortsightedness is not necessarily snobbery. The pursuit of knowledge should not be punished. Nor should he be called a colonialist, for that matter--he didn't advocate taking over the place.
Me, I'd go with shade, big fans, and ice-cold beverages. But I don't know if there's too much sand for the fans.
-- IANAL, this isn't legal advice, and definitely isn't legal advice for you. Also, Squee!
slighly off-topic: two major cities - tel aviv and bangalore - cut down large numbers of trees in order to make room for more people. the immediate result was a rise of 10 Centigrade in bangalore (from 45C to 55C).
Speaking of 45C... you'll never EVER see a temperature in Egypt officially reported as 45.0 degrees C or higher. The reason is that there's a law on the books that says that if it's that high, it's "too hot to work" and thus people need to, by law, given the day off while it's that hot if working w/o A/C. So the "solution" for the government is to never report higher than 44.9C.
Really. My wife and I were in Egypt last year (an awesome tour), and a thermometer somebody had showed 58C (this was near Farafra in the western desert), but the digital road sign said the temperature was 44.9. We asked about it, and the locals told us what I just said above.
So up to 45 in Cairo? Sure, but probably even higher.
I thought the sand niggers / dune coons were adapted to dealing with temperatures like this.
As with all technological problems someone at Burning Man has already prototyped an elegant solution.
Towel on face. Then pour water on it.
Have gnu, will travel.
By the way, one of the reasons of energy crisis and global warming is the mass usage of medieval clothing, not only in Middle East, but in Western cities too.
Washing, drying, dry-cleaning, ironing all those zillions of suits and long sleeve shirts for office takes enormous amount of energy. Let alone air-conditioning offices for these suits.
Why not to introduce business shorts and short sleeve shirts for summer weather?
This is sort of like someone from Florida giving advice for dealing with a blizzard to someone who lives in northern Canada.
BS. The article mentioned temperatures up to 111 F. Millions who have grown up in inland southern california see that quite often in the summer time. And when they visit Phoenix in the summer these people think: damn its hot. So actually there are plenty of Americans who have comparable or even more extreme experience.
FWIW, devices deploying a fine mist in Phoenix seemed to work quite well in the summer.
You see these things at county fairs and I've even seen them at a coffee shop. First, unlike a tent it wouldn't block your view. That's important because it's a protest arena so you want to see and be seen. Secondly, it's fairly lo-tech and probably not very expensive. All you need is water, something to pump it through the little plastic tubes, and something to prop up the tubes on.
One drawback is that this requires some "infrastructure". You need to replenish the water and you need to power it. Perhaps handing out spray bottles, super-soakers, and hats is a better idea. The party with their logo on the cooling freebies wins the election. :)
cut down large numbers of trees in order to make room for more people
The cut down the trees to make room for cars. Most of the space in almost all cities is devoted to the worship of the car. Roads, parking lots, garages. It is actually quite ridicules when you think about it.
Tarps, fans, salty foods, water. You sweat, the wind cools you. Unless you build insulated buildings with HVAC systems, that is the best you can do.
The goal is to keep people cool, not a place. Here's one cool option (pun intended).
People have been making "cool ties" for several years now. Basically a cloth tube with a little bit of water absorbing polymer inside (available at gardening centers in the US). They hold a lot of water and create a little evaporative cooler for your neck. Like soaking a towel, but more water with less dripping.
People make them and send them to soldiers in Iraq and Afghanistan. there are versions for necks, helmets, even vests.
Here are some detailed instructions: http://www.watersorb.com/polymer_cool_neck_bands.htm
The world is made by those who show up for the job.
Design a system where you pour water into a personal container, and have a system of pipes from that container which distributes the water over the entire surface of the skin and evaporatively cools the person.
Oh, wait, evolution already did.
Before Tel Aviv was founded there were mainly sand dunes there, so the trees that were cut down were actually planted by the city. In Tel Aviv there are still many trees in the streets and also a large park along the Yarkon stream, so there was no real change in the place available for migrating birds to stop. The birds tend to skip the cities (they prefer food from fish ponds and grain from the fields over the nightlife Tel Aviv can offer) and land to rest in other parts of Isreal, mainly the Hula lake and the fish farming areas between Tel Aviv and Haifa. The trees in Tel Aviv metro. have no real effect.
Piss on a towel, wrap it round your head. Basic desert survival technique.
Of course, it may get pretty smelly around there after a few days.
The Square, The Square, The Square is on fire!
We don't need no water, let the M_F_er Burn!
Cool the square by transporting the heat to elsewhere where it can be used to generate power which can be used to move the heat transport agent (heatpipe principle maybe?)
Pass out little bic lighters and have everyone come out at night. Feel the love.
You could bring in moss, grass or sod with seeds or other plants and made green isles or islands... sounds expensive/laborious but would be quite memorable especially seeing as you will not be going anywhere for a while, and have a surplus of labor. a mid term plan of repurposing the city from moving cars and people to standing people, in this case gorilla landscaping, it might be worth it to make the place more useful to the people using. It might be a psychological boot to the people to have have a plan to organize around other than anger and waiting.
tl;dr
bringing in plants and soil would improve cooling, make a statement and change the streets to be useful for people since cars will not be there in mass any time soon, though would need to tend to the plants and water to spare for them
Recently released report shows that USA spends $20,000,000,000 a year in Afghanistan for air conditioning alone.
Perhaps you could get in on some of that?
Yes it was all a wasteland, a howling wilderness before it was settled by the noble, selfless Jews who made the desert bloom.... without stealing anybody else's water, or land - at least no one who mattered - or anyway, certainly no one who could fight back. Selfless Jews, unaccountably harassed in later years by the cowardly terrorism of little brown untermenchen, walking around to deliver bombs instead of properly dropping them from planes on children like real Yehudi herrenvolk do.
And its spelled "Israel", not "Isreal", O Hebrew sage.
"Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?" - Patrick Henry
For the open square, a regular grid of telephone poles with staggered height sheets of white canvas or translucent plastic. This allows unobstructed air circulation while blocking 50% to 80% of the sun's heat.
For passive ventilation, 4 tall telephone poles arraigned in a square with transparent plastic sheets forming a square chimney. Inside the chimney have sheets of black plastic forming an X between the poles. The sun's heat on the black plastic will cause an updraft that will draw cooler air into the square through the gaps between the staggered height tents. There should be a number of chimneys arraigned around the square to provide enough draft to handle the heat generated by the people in the square [10,000 people = 1-5 megawatts].
Water hoses can be strung between the tent poles with mist sprinklers spraying the people in the square.
The temperature may be 111F outside but it will be less than 90F under the shade of the tents.
What I would do is any of the following: Make shade, Make breeze, or add mist. Tarps and poles help the first. Large fans with the second, and using water sprayed over a large area would help cool the air, cool the people, and cool the surfaces. If you combine fans, shade, and mist, you can cool off even 120+ temperatures to a reasonable level over a large area at minimal cost.
Where is the mod rating for "scary"? Also,
If everyone carried a white balloon overhead, and they were packed closely enough, it would reflect the sunlight back into the sky.
>>> the immediate result was a rise of 10 Centigrade in bangalore (from 45C to 55C)
Really? I've been living in Bangalore for the last 10 years and have never experienced or heard of 45C temperatures. In fact it would be news if the temperature got anywhere close to 40C.
Not to say that trees aren't getting chopped to accommodate more traffic.
The highest temperature ever recorded anywhere in India was just south of 52C... and Bangalore is a place with very temperate climate.
http://en.wikipedia.org/wiki/List_of_weather_records#Highest_temperature_ever_recorded
Bangalore never gets above 40 C.. and very rarely does it get over 35 C. It is true that a large number of trees were cut down and the temperature did go up, but it wasn't anywhere close to the 10C that you claim.
http://www.port-a-cool.com/ is the commercial version, but it's basically some giant fans blowing through a constantly wet evaporation surface.
On second thoughts, I just checked the climate data and it looks like Cairo tends towards humid heat at this time of year, so that's actually not going to help very much at all.
Back to shade then.
Hexayurt - open source refugee shelter,
Vegetation in general will cool down an area. Less concrete and more trees will have an impact.