A couple of the negative aspects of cloud computing came to the fore this weekend as circumstances conspired to bring a number of major sites down.

The first challenge came in the form of storms associated with the heatwave currently oppressing much of the US.

Violent storms in Virginia took out power to Amazon’s Elastic Compute Cloud, which caused major sites like Netflix, Pinterest, SocialFlow and Instagram to go down.

Although the power outage was expected to last several days, Amazon was able to get some of the sites up and running within a few hours – although Instagram was down for well over a day.

And yesterday, some sites were still down after a leap second was added to the universal clock on Saturday evening.

Major services like LinkedIn, Foursquare, Reddit, Mozilla, Yelp and Gawker all reported technical issues when the second was added.

The leap second was added to Co-ordinated Unversal Time to keep to aligned with solar time. The last time a second was added was 2008.