Cloud Appreciation Society

One of my Christmas presents was 'The Cloudspotter's Guide' by Gavin Pretor-Pinney and published in 2006 by Hodder & Stoughton on behalf of the cloud appreciation society.

This site includes an excellent example of a subject-specific photo site, with many excellent photographs of cloud formations, optical effects and associated phenomena. The site was interesting in the context of the DSA module because it combines the problem of creating a photo site with the problems of tagging and categorising information, so I thought I'd write a review of it here, as perhaps as an example of what might have been included in theFlickr review. Next year I think I will base the coursework on a selection of sites like this rather than a monster site like Flickr. I welcome suggestions.


The home page is a page featuring the last photo to be loaded.

Search by category and by partial string match within the title string are provided on this page. These lead to two different album pages - a paged layout in the case of the category, a list with thumbnails and titles in front of the page from which the search was launched in the case of the title search. Its not clear why there should be two different approaches. Usefully, the category selector shows the number of photographs in that category.

Direct links to the categories to which the current image has been assigned are provided and a featured category (Cloud Lookalikes) is at the top.

Each page includes a selection of other photographs. The criteria appears to be just the adjacent photo accession numbers and is not based on any criteria of similarity, but nevertheless it does encourage serendipitous browsing. Curiously the aspect ratio of these photos is determined by that of the main photo, leading to mal-shaped images.

Clicking on the photo rather surprisingly links to the next photo in sequence. There is also a 'Previous Page' link which is functionally a back button - it is not quite clear why this is included since this is a standard browser button. Perhaps Next and Previous links (in the accession sequence) would provide a better navigational mechanism.

A search (or link) to a members photos would be useful.

Photo Data

Images are jpegs at medium and thumbnail resolution.

Meta data include the name of the copyright owner (or is it just the member?), a descriptive title, data and time (but of upload I would guess, not of the photograph itself). The title can contain links e.g. to related sites.

Each photograph is related to several categories.

It is a pity that the photographs do not appear to be geo-coded, because it would be nice to mash these up with Google Earth. There is often a description of the place which could be translated through a geo-coding service. Since some photos are taken from planes, altitude data is needed too.

Tagging and classification
Each photograph is classified into one or several of around 40 categories and hence linked to other photos in the same category through that category. The category system itself is interesting as a information construct. On the surface, it would seem that it would benefit from some hierarchy. e.g.

* All photos
** Cloud Type
*** Cumulus
**** Kelvin-Helmholtz wave cloud
** Cloud features
*** Contrails
** Time-of-Day
*** Sunrise
*** Sunset
** Optical Effects
*** Rainbow
*** Halo
and probably others.

It also seems that some category meta-data is embedded in the name - the numbers on Cloud types is a reference to the Chapters in the book. Clearly a general description of the category itself could also be part of the overall data structure. The book provides a hierarchical classification of cloud types which would be useful to include. There are also occasional synonyms embedded in the name -eg Mamma (also know as mammatus) which could be treated uniformly as category meta-data.

The task of classifying each photo into these categories is not open to the public or members but is seen as an expert task. However there are places, such as in the category of 'Clouds that look like things' where folksomony would seem to be appropriate. Photographs also sometimes contain objects e.g. balloons, planes, boats for which arbitrary tags seem suitable.

Rather surprisingly, photo upload, even by members, is not supported, and photos have to be emailed to the webmaster with accompanying meta data for upload and categorisation.

Rating and comments
The public can easily rate photos and add comments. The comments are generally expressions of appreciation of no interest to anyone but the photographer. There is no information on the basis of the rating - indeed all photos I've seen are rated 4.It is not clear what value this adds or indeed what is being rated - the photograph or the subject.

Compatibility and Accessibility
Images have alt tags but these are the copyright names, not the description of the image which would better aid the reader.

There are keywords in the page meta data but these are not photo specific.

XHTML compliance - main photo page shows 1 error and 17 warnings. Typically these are problems with table and div tag nesting and problems with & . The error is a non-HTML tag.

The display of some characters in the title is broken (on Firefox and IE) e.g this

API and Feeds
The site provides RSS2.0 and Atom feeds of the latest photo additions and a Feedburner link.

The scripting language is PHP, images are held as files, not held in the database. Not sure what database is used (probably MySQL?). CSS is used for styling. Small amount of Javascript e.g. for GIF rollover on the rating buttons and call to update the rating. One function is defined (flip) which is not used.

The program architecture uses a single index.php script with a parameter to determine what page type to return, rather than multiple scripts. Interesting design issue here.

Data Model