The Wedding Diaries: The Science behind “the Curse”

In yesterday’s post we presented our evidence for the existence of “the curse” – the curious twists of fate that seem to conspire against us at every turn. Today we bring the scientific proof! When we decided to get married in La Palma we were booking a wedding at a destination where it rarely rained, was hardly ever windy and was basically pretty sunny and nice! Things didn’t exactly go to plan! Now don’t get me wrong, we still had an amazing week and as it turned out nothing was really affected, but the weather was rather far from advertised! Upon our arrival we  couldn’t believe it when we were almost immediately met with what was, according to the father of the groom in a much coined phrase, the first rain in two years, but things were worse than we realised!

Now, it’s all very well me telling you about weather systems but, let’s face it, I have no idea what I’m talking about! Fortunately amongst our wedding party was the perfect woman for the job! Over to Leanne Wake, Doctor of…scientific stuff… to explain just how the heck the curse happened!

‘I’ve been coming here for over 12 years…..I’ve never seen it rain in Puerto Naos during this week in October’ – FOTB, sometime before take-off

Fair enough, I thought. When researching climate and weather issues, sometimes memories can be just as valuable as an almanac of numbers and statistics. They always say there is one thing you can’t choose on your wedding day, and that is the weather. It is at this stage we must make an important distinction between weather and climate – because it’s often the latter couples look at when making the decision to marry in far-flung locations. The difference between weather and climate is mainly a matter of time frame and predictability (thanks NASA website); climate is the long term average of daily weather, and how the atmosphere behaves over time, whereas weather relates to the short term, often unpredictable aspects of the ocean-atmosphere system.

I’ll try not to make this sound too much like a science lesson, but we’re going ask whether the FOTB’s prediction was made with ill-founded confidence, and if he made his decision based on climate or weather.

You’ll notice that the Canary Islands are located at 28 Degrees North just 500km from the coast of Africa and the Sahara Desert, yes DESERT, so you’d be forgiven for thinking that you’ve got a good chance of bone-dry conditions for your wedding day. But why is it so dry in these latitudes? You have Mr Hadley to thank for that.

As the proprietors of this blog are tea-obsessives, I’ll put it in their language.

Boil your kettle. What happens? Hot, damp air rises (as it is less dense).

Take your boiling tea to the fridge to get your milk….. watch the steam from the cup. It moves out of the kettle towards the fridge.  (or it should – I haven’t moved from the sofa to test it)

This is the basis of atmospheric circulation and how it has helped to the climate of La Palma hot and fairly dry. Hot, damp air rises from the Equator through the lower atmosphere (creating and area of lower pressure at sea level). Because of the large amount of water involved in creating low pressure systems, they are associated with cloud, rain and general meteorological mingingness.

‘It’s like raaaaiiin, on your wedding day’ Alanis Morrisette, Musician and psychic

This moist air from the Equator sinks at areas further north (creating areas of high pressure – imagine being crushed by a big wedge of air falling upon you).  As most of the moisture has been rained out by the time the air package has travelled north and began sinking, areas of high pressure are associated with dry, calm conditions. These areas of ‘high (H)’ and ‘low (L)’ pressure are prevalent features on the Earth and are responsible partly for the locations of our hot deserts and rainforests. Well it just so happens that La Palma is delightfully situated in one of these high pressure areas. As a consequence, la Palma enjoys average conditions which would placate any bride and groom worried that they might end up with an ‘Ironic’ wedding.

Hadley Cells, badly superimposed by L Wake onto a Google Earth screen shot

Data of sea-level pressure for the Octobers of the past twelve years seem to bear this out. Also, the average 5 rain-days for October in La Palma over the last decade would encourage the most cautious that their big day would most probably be unspoilt by the old H₂O.

You will see from this graph that the daily lowest value of sea-level pressure (SLP) wiggled between 1010 and 1020 mBar. Up until the 26^th, the wedding party remained happy that there was a good chance the weather would remain decent for the big day. The black line is the average value of the lowest daily sea-level pressure for October for the period 2000-2012. The black dotted lines you see on this plot are called +/- ‘3-sigma’ (geek speak), and in some ways are a measure of certainty; in essence, 99.7% of all the daily low SLPs during the Octobers of the past 12 years fell between 1006 and 1026mBar.

Along came the rain and washed the Bride (r) out

Fast forward to October 30^th, and a line has been crossed in more ways than one. Sea-level pressure plummeted to 996Mbar (a value in the 0.3% of the low SLPs for the past twelve years) – bringing with it rain (we are talking several tens of mm in a few days, when the average for October is 30mm), gusts of 60-80 mph and a blanket of fog which, we must add, made the ‘First Look’ photography look absolutely ethereal. What was also unusual about this week was that the ocean to the south of the Canary Islands, along with much of the Northern Atlantic was 3 Degrees Celsius warmer than usual – turning this part of the ocean into a giant kettle (so to speak), releasing lots of moisture to the atmosphere. It could have been worse, of course. The Bride and Groom could have opted for a New York wedding and been on the receiving end of a whopper of a low pressure system with its own name: Hurricane Sandy!

So, we cannot blame the FOTB for this climate cock-up: he has based his statement on the average conditions in La Palma for the last 12 years – and failed to predict the weather – something which remains a challenge for scientists to this day. In conclusion – you should always prepare the worst and ask yourself these questions:

1. For an outdoor wedding, is there somewhere to run with your champagne and canapés when dark skies appear? Such as a church which doesn’t mind being used as a disco/pub? (ahem)
2. When choosing a photographer/videographer ask them for examples of their work which they shot in challenging surroundings. Are you confident that whatever the weather, you will come out with some excellent photos?
   
3. Remind the guests about preparing for adverse conditions (e.g. umbrellas, hairspray and Marilyn Monroe moments)

Fortunately for Matt and Dom – all of these points were covered!

Data for this report comes from Wunderground.com and worldweatheronline.com