With high atmospheric pressure giving us a prolonged period of hot weather, it’s a good time to calibrate our barometer, something that I’ve never got around to doing since I inherited it from Barbara’s dad.
According to the Met Office website, the pressure today should remain stable at 1020 millibars, which is equal to about 30 inches of mercury, classed as ‘Fair’ on the barometer. Our reading was just 10 mbars out, so it needed no more than a quarter turn of the small screw on the back to put it right, which is pretty good after twenty or thirty years.
It’s an aneroid barometer so the adjustment changes the tension of a spring which is there to prevent the pressure-sensitive metal chambers inside it collapsing.
It would have been impossible to calibrate the thermometer on the day that I drew this sketchbook page in early spring, 2014, when a low pressure system was sweeping across Britain.
9.45 am, looking east, wind from south-west, 19°C: This altocumulus cloud has formed as a layer, so it is classified as stratiformis. The ripples mean that it’s also undulatus and, finally, because the sun is visible through the cloud, it’s translucidus.
10.30 am: Three-quarters of an hour later the sky has filled with stratocumulus. We don’t get thunderstorms but there are a few rain showers later in the day.
As you might have guessed, my current bedtime reading is Clouds by Eric M. Wilcox.
After my weekend watercolour workshop, it’s hardly surprising that Monday morning starts with me seeing potential subjects as the sun melts away the fog. But we’re setting out with places to go and people to see, so I’m sketching indoors again today.
The cushions provide me with a landscape in miniature.
Through the top of a window I can see the branches of an ash, which is still hanging onto a few of its keys.
I add some crayoned colour to my cushion landscape.
Late afternoon and I pull in at the viewpoint to photograph the cloudscape as we cross the moor top between Hawes and Langstrothdale.
“I think those clouds are caused by air rising as it moves over a hill,” I suggest to the man who has pulled in just behind us to photograph them on his iPad, “I’ve been reading The Cloudspotter’s Guide, but I can’t remember what they’re called.”
“That’s right; you are a cloud spotter?”
“No . . . just nutty!”
Just as I’ve got myself back in the car and out of the cool breeze, I notice another cloud-spotting feature to the left of the lenticular cloud that is hanging above Ingleborough and I grab my camera.
“Have you seen the sun-dog?” I ask the man with the iPad; “They’re caused by ice crystals in high clouds refracting the light and they always appear at a certain distance from the sun – I think it’s something like 23 degrees.”
“I wonder if that’s because we’re at 53 degrees north?” He surmises.
I wasn’t too far out, it’s 22° but the phenomenon is a halo effect caused by tiny ice crystals in translucent cloud, so the effect is independent of latitude.
Sunset over Langstrothdale
Half an hour later I take the opportunity to photograph sunset over the top end of the dale from the first floor window of our barn conversion accommodation at Nethergill Farm.
It’s the first time that I’ve tried the ‘sunset’ setting on my camera. It might have warmed up the colours a little but it’s more successful than the camera’s default setting which attempts to adjust the exposure to make the scene resemble regular daylight.
I set up the telescope in the last patch of afternoon sunlight on our back lawn and catch an image of Mercury mid-way through its transit across the Sun. This is the first time that I’ve seen Mercury: as we’re in a valley, we’re never well placed to see its brief appearances at dawn and dusk.
I don’t have a solar filter for the telescope so I project an image onto a sketchbook page, then photographed the image. I feel that it’s safer to project anyway: a friend accidentally burnt out the lens of his smart phone when he moved his telescope into position, having briefly removed his solar filter to make it easier to level up the shadow. That’s £70 for a replacement lens but you can’t replace an eye as easily.
Squeezing my camera in between telescope and sketchbook to take the photograph resulted in an oblique view of the solar disc so I skewed and stretched the image in Photoshop to fit into a yellow circle (top image).
If we could see the Earth’s silhouette alongside that of Mercury, it wouldn’t be much bigger than the larger sunspot (left).
Seeing the progress of Mercury across the solar disc gives an impression of the scale of the Solar System; 99.8% of the mass of the Solar System is contained in the Sun.
We’re disappointed that, with a near total eclipse due at about 9.30 this morning, cloud is covering the eastern sky but we’ve located our eclipse glasses from 1999, so, with ten minutes or so to go, I try looking towards the bright patch in the bank of cloud.
I’m astonished and delighted to see, in sharp focus, the disc of the Sun neatly perforated by the eclipsing Moon.
As it progresses towards near-totality, the crescent shrinks to a slither which reminds me of the end of a finger-nail but which has been better described as a smile in the sky.
It gets surprisingly dim considering that there’s still a blazingly bright crescent behind the thin cloud. The birds go quiet as if tricked into thinking that night is fast approaching.
A Second Sunrise
As the Sun’s disc begins to reappear there’s strange kind of second sunrise. It’s like sunrise but more brilliant, because the Sun is already quite high in the sky. The brightness over the fields reminds me of sunrise on the east coast where light reflected off the sea intensifies the growing brilliance.
I’m reminded not just of the total eclipse in France sixteen years ago but more recently of an annular eclipse that we viewed from Sandsend; a ring of fire rising above a hazy North Sea.
Back in 1961 I was lucky to be able to observe a partial eclipse by looking through smoked glass in the school playground at St Peter’s Junior’s, Horbury. We were told then that the next total eclipse visible in England would be visible from Cornwall in 1999. It seemed an impossibly long time in the future but I remember thinking how amazing it would be to see it. When the time came, the easiest option was for us to go and stay with my penfriend from schooldays, Philippe, in Lille. We made the right choice because on the day thick cloud obscured the eclipse in Cornwall.
Veils of grey cloud in ripple-mark patterns scud along from the south-west against a pearly glare which is all we can see of the midday sun. The wind up here at Birstall retail park flattens the spring loaded signs, bends the trees and grabs at the doors of the Pizza Express so that the waitress has to reset the door-opening mechanism.