Thursday 14 May 20 – Early – Cumulus

Today is a day when you can watch the clouds develop.  The aristream is unstable with respect to sea surface temperatures.  There is a hard edge to the lifting condensation level and spirals of cumulus development are evident.  Within the space of 5 minutes you can witness cloud currents grow, mature and fade.

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Monday 11 May 20 – Cumulus and Cumulonimbus

Herne Bay and Reculver.  Cold, near gale force wind with good sunny spells but some showers too.  Featured image shows cumulus with blue sky to the left but the onset of a shower to the right.  Note the reduction of visibility under the shower and the loss of a hard horizon.  I have no image of the vertical extent of the cloud but there are strong gusts and showers, so … cumulonimbus.  In between the showers are smaller cumulus clouds, but always in a cold blast.

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This bitter north easterly across the North Sea has reset the seasons back to winter after some summer like days last week.

The satellite image for the same time shows a classic pattern of deep convection with separate convective cells dappled in the flow.

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Tuesday 5 May 20 – Cumulus, Stratocumulus, Cirrus

Herne Bay, light breeze and fair weather.  Cirrus dominates the skyscape with shallow streets of cumulus forming closer to the sea surface.  More clouds out at sea.

Chart and satellite picure combo show anticyclone in the North Sea and a feature analysed as an upper occlusion over the channel; there is much upper level cloud associated with this streaking past above in the upper winds.  This system just visible to the South.

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Monday 4 May 20 – Towering Cumulus

Herne Bay, fine weather, cool breeze.  Morning picture, set as featured image, shows Towering cumulus out in the North Sea.

Satellite picure shows the clouds out of our coast.

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Slightly hazier conditions later in the day.  Patches of cumulus and stratus form over the sea

 

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Clouds – Thursday 16 April 2020

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Hampton, Herne Bay at 1430.  Light winds, cool temperatures feeling a little bit clamy.

The North Sea is a little bit murky today, it almost felt like mist.  When does mist and murk become a cloud? The answer is, when it is thick enough to be fog.

The visibility is not brilliant today and there is no hard horizon.  The clouds are a little shapeless and grey.  Mostly low level stratocumulus and stratus.  There are occasional lighter patches in the sky and even a hint of blue in places; the cloud layer is not thick and merely the result of the cooling effect of the North Sea on moist air moving up from the south, see chart and satellite image below.

Towering Cumulus over the London Array

Towering cumulus over the London Array, outer Thames Estuary.  Complex low pressure lies over the North Sea countries.  Watnall balloon suggest unstable to sea surface temperatures with drying up at about 15,ooo ft.  AVHRR image, 1420Z, picks out this development at the end of a cumulus boundary running through the south east.

Jet-stream Cirrus from warp and weft of Atlantic air currents illustrate traditional forecast rules of thumb

One of the tricky things about meteorology is that it happens in three dimensions above the surface of a rotating sphere.  In fact, if you add in time, it is four dimensional.  Yet we only have two dimensional graphics from which to build our understanding of it; its rather like building the picture of a garden viewed only through the narrow gaps in boundary fence.

This featured picture has a stable south westerly jet-stream flow aloft, marked by cirrus which weaves itself across a lower level unstable north westerly from the direction of Cape Farewell, the southern tip of Greenland.  Such differential motion of low and high level clouds give rise to traditional seagoing forecast rules of thumb and allow an observer to detect whether they are ahead or astern of a storm.  Of course, a peek at the ships log might tell them that.

Jet stream is shown here from Earthnullschool’s 250mb streamlines.  This matches the shape of the cirrus in the satellite picture above.

250mb stream lines, 29 Mar 16, ENS.
250mb stream lines, 29 Mar 16, ENS.

Whilst below the 1000mb streamlines are:

1000 mb flow, 29 Mar 16, ENS
1000 mb flow, 29 Mar 16, ENS

In this case, cumulus at lower levels moves from the north west whilst cirrus at high levels comes from the south west.  The area does lie to the south west of the complex Atlantic low in the aftermath of storm Katie and pressure is building heralding more settled weather to come.