Wicken Fen. Hazelnut Sourdough Bread. Weight of Water in Clouds and Rain

Apollo 13 medal with flown metal by Moonpans, seen at Quekex

Prime Minister Theresa May still in post and now receiving advice from both wings of the party. One recommendation - sack Boris for being more brexiteering. The other, sack Hammond for being too soft on Brexit. EU- GB negotiations to start again this week.

We went to Wicken Fen today, taking in a new walk that was a relaxing wander through a woodland with a profusion of sloes. One couple was busy harvesting the fruit with an eye to flavouring gin back at home. According to recipes online, the minimum time for steeping the sloes in sugar and gin to achieve a good flavour is 3 months in a dark place.

Enjoyed a tea and coffee cake for me, blueberry cake for Jane before returning home. Baked a mixed loaf of sourdough bread (helped along with a bit of yeast), using 200 g rye flour, 100g  strong white wheat  bread flour, 100 g strong wholemeal wheat flower, 146 g Camilla sourdough,  8 g salt, a small handful of ground hazelnuts, a small handful of whole hazelnuts, a desert spoon of honey and a splash of olive oil. It doubled in 4 hours. Knocked back and left to rise in a round tin for a further 3 h. Also baked some fantastic Yorkshire puddings today for evening meal.

With clouds scurrying to cover the initially blue sky, Jane and I were wondering about humidity, dew points and the amount of moisture in clouds. Checking this evening, it seems that humidity measurements are dependent on air pressure and temperature. Today's temperature of about 15 degC and 1012 air pressure meant that at 1kg of air could hold about 11g of water vapour at 100% humidity. In the tropics, this would rise to about 30g water per kilogram air. At 1 degC, close to freezing, this would only be 4 g water per kg air.

• Assuming the average molecular mass of air is 29, then 29 g of air (1 mole) would fill 22.4 litres. 
• 1kg of air is 34.5 times the volume, 772 litres, or approximately 0.77 cubic metres.
• So, at 100% humidity, the air today would have contained 11 g water per 0.7 cubic metres air

If we simplify things a lot and say that 1 cubic metre contains about 1 kg air and 10g water when saturated then

• For a cube of fog 10 m x 10 m x 10 = 1000 cubic metres: It contains 1000 kg (or 1 ton) of air of which 10 kg are water.
• For a large cloud of 1 km x 1 km x 1 km (1 cubic km or 1,000,000,000 cubic metres): It contains 1,000,000,000 kg air (1 million tons) of which 10 million kg (10,000 tons) are water.

And that is an underestimate.

Of course, not all this water falls as rain, so perhaps we should consider the weight of water that falls on a square kilometre. 

• A precipitation of 1 mm over a square km is equal to 1,000 tons of water
• 10 mm rain over a square km is equal to 10,000 tons of water

Editing my pictures from the Quekex yesterday, a bit disappointed with the photos of both the moon and mars rock fragments. However, the medal I saw commemorating the Apollo 13 mission came out well.