Wind Tower

[dubaiphil]

A 6 shot pano with the 85mm f1.4D, showing a wind tower in Bastakiya, Bur Dubai:

[merlin1027]

Very nice shot.

[Downrigger]

Neat image. Good lines and nice contrast. Maybe you can explain the "6-shot pano" though. Obviously it helped you achieve this nice result. But I would've thought this was a single, perhaps cropped, shot with that 85mm (?).

[John 2]

Nice shot Phil. What did you stitch it with?

[dubaiphil]

Thanks - here's a half sized version which you can zoom in on to see the reason for shooting as a pano. Plenty of detail in there. It's not possible to take the shot with a single 85mm frame due to the building behind me when I shot. Stitched with PTGui, and then into Photoshop

[Downrigger]

Makes sense, and impressive how you kept the perspective effect minimized.

[Bobobird]

Hi Phil, long time no see.
Superb shot as usual.

[Donald]

Beautifully captured and processed ... as per usual.

What I'm most fascinated about is - What is a Wind Tower?

[dubaiphil]

For Donald and anyone else interested courtesy of Wikipedia:

A windcatcher (Persian: بادگیر‎ bâdgir: bâd "wind" + gir "catcher", Arabic: ملقف ‎malqaf in Egypt[1][2]) is a traditional Persian architectural element to create natural ventilation in buildings.[3] Windcatchers come in various designs: uni-directional, bi-directional, and multi-directional. Windcatchers remain present in many countries and can be found in traditional Persian-influenced architecture throughout the Middle East, including in Pakistan, Afghanistan[4] and the Persian Gulf states.

Windcatchers tend to have one, four, or eight openings. In the city of Yazd, all windcatchers are four- or eight-sided. The construction of a windcatcher depends on the direction of airflow at that specific location: if the wind tends to blow from only one side, it is built with only one downwind opening. This is the style most commonly seen in Meybod, 50 kilometers from Yazd: the windcatchers are short and have a single opening.
To keep buildings free of dust and sand blown in from the desert, windcatchers were built facing away from the wind.[9]

The windcatcher can function in three ways: directing airflow downward using direct wind entry, directing airflow upwards using a wind-assisted temperature gradient, or directing airflow upwards using a solar-assisted temperature gradient.
Downward airflow due to direct wind entry[edit]
One of the most common uses of the windcatcher is to cool the inside of the dwelling; it is often used in combination with courtyards and domes as an overall ventilation and heat-management strategy. It is essentially a tall, capped tower with one face open at the top. This open side faces the prevailing wind, thus "catching" it, and brings it down the tower into the heart of the building to maintain air flow, thus cooling the building interior. It does not necessarily cool the air itself, but rather relies on the rate of airflow to provide a cooling effect. Windcatchers have been employed in this manner for thousands of years, as detailed by contemporary Egyptian architect Hassan Fathy.[10]


A windcatcher and qanat used for cooling
Upward airflow due to temperature gradient[edit]
Wind-assisted temperature gradient[edit]
Windcatchers are also used in combination with a qanat, or underground canal. In this method, the open side of the tower faces away from the direction of the prevailing wind (the tower's orientation can be adjusted by directional ports at the top). By keeping only this tower open, air is drawn upwards using the Coandă effect.
The pressure differential on one side of the building causes air to be drawn down into the passage on the other side. The hot air is brought down into the qanat tunnel and is cooled by coming into contact with the cool earth[Note 1] and cold water running through the qanat. The cooled air is drawn up through the windcatcher, again by the Coandă effect. On the whole, the cool air flows through the building, decreasing the structure's overall temperature. The effect is magnified by the water vapour from the qanat.
Solar-produced temperature gradient[edit]
In a windless environment or waterless house, a windcatcher functions as a solar chimney. It creates a pressure gradient which allows hot air, which is less dense, to travel upwards and escape out the top. This is also compounded significantly by the diurnal cycle, trapping cool air below. The temperature in such an environment cannot drop below the nightly low temperature.
When coupled with thick adobe that exhibits good resistance against heat transmission qualities, the windcatcher is able to chill lower-level spaces in mosques and houses (e.g. shabestans) in the middle of the day to frigid temperatures.
Directing airflow upwards using wind-assisted or solar-produced temperature gradients has gained some ground in Western architecture, and there are several commercial products using the name windcatcher.

[Wavelength]

Awesome, Awesome