Ted and Judy


A Day at the Beach – A Cloudspotter’s Joy

There are many things to enjoy at the beach: the sand; surf; long walks and fishing, but above all is the lovely expanse of sky with its ever changing cloudscapes. Something is always happening and the sky could be regarded as God’s screensaver.

Earlier this year Judy and I spent a few days at Currumbin Beach and were treated to some interesting cloud systems. Many days were clear and almost cloudless, which is unusual for the beach and the predominant cloud formations were a series of beautiful high-level Cirrus clouds.

In addition to the Cirrus there were two storm fronts, the most dramatic of which we missed because we were went walking without cameras – tut tut. The one we captured arose very unexpectedly from Coolangatta and had a very dark roll cloud underlying a sunset-lit Stratocumulus formation in advance of a storm front.

We were on our way back along the beach from Tugun at about 5:45pm when the beach suddenly became very dark and it seemed like the end of the world. All of this happened within 40 minutes. The storm front eventually passed out the sea and continued north where it made land fall again and had its way with the north coast beaches.

Cloud Classification

Cloud viewing is something we have always enjoyed and some years ago decided to look for a guide to cloud classification so that we could more fully appreciate what we were seeing. In this search we found The Cloud Spotter’s Guide which is an official publication of the Cloud Appreciation Society. The Cloud Spotter’s Guide has been replaced by The Cloud Collector’s Handbook available for purchase via the Society’s web site. Membership of the Society is open to all and the joining fee is small.

The web site has a number of interesting areas to peruse including a photo gallery to aid cloud identification. The Cloud Collector’s Handbook has a cloud spotter’s score sheet allotting graded points for various cloud formations. This score sheet adds to spotting enjoyment, sort of like a twitcher’s log of birds seen with extra points for rarity.

Cloud classification is complex, but it is easy to achieve much satisfaction from learning the basic cloud groups without descending into the detailed areas of sub groups – species and varieties. This newly acquired cloud knowledge has increased our daily enjoyment of the world around us and we urge you to look up often and enjoy the show.

Photo Gallery

The photo gallery below has some of the clouds observed on our February Beach visit and we intend to add new cloud blogs as we accumulate photos.

The three layers of cloud are based on height and since the sky often has mixtures of clouds, height can be best interpreted one against the other. Roughly the heights are as follows –

  • Low level clouds are at about 700-1000 metres.
  • Alto the middle level clouds at about 2000-6000 metres.
  • Cirrus, the highest at 8,000 metres and above.

These heights vary with latitude, e.g. the troposphere is higher over the equator than over the poles.

Lower Level Clouds

Cumulus clouds exist as single, isolated (detached) puffy clouds. They may be aligned in lines (Cumulus Radiatus Cloud 1) or they may be large extending vertically to be taller than wide. These tall Cumulus clouds are called Cumulus Congestus (Cloud 2) and may evolve into Cumulonimbus storm clouds (Cloud 3). The two can be distinguished by the sharpness of their upper margins – in Cumulus Congestus the margins remain clearly defined, in Cumulonimbus the upper margin is diffuse and filmy, and may reach the highest cloud level (troposphere) where it becomes flattened (anvil).

Stratocumulus clouds appear as patches of joined, cumulus-like clouds. They may form clumps (Cloud 4) or be extensive. Their base is flat and the upper surface is unevenly made up of rounded lumps or rolls. Clouds 5 – 6 show the evolution of a Stratocumulus cloud bank over Tugun between 5:40pm and 6:20pm. A rolling cloud in advance of a storm front eventually developed at the base of the Stratocumulus layer (Cloud 6). In this shot the Stratocumulus clouds on the upper right are extending vertically and their upper surfaces are less well defined. They are changing into Cumulonimbus storm clouds.

Cloud 7 is a continuous Stratocumulus cloud layer showing crepuscular rays of sunlight through gaps in the cloud at dusk over Currumbin Estuary.

Middle Level Clouds

In Cloud 8 there is an extensive bank of low level Stratocumulus cloud out to sea and parallel to the horizon. In our experience this cloud formation and its arrangement are common at the beach. Above that is a small, linear patch of sheet-like Altostratus cloud, which is being stretched towards the beach by winds to become Altocumulus (clumps). Altostratus clouds may completely cover the sky and be dense or thin.

Cloud 9 is an isolated, sunset-lit Altostratus cloud.

High Level Clouds

Cirrus clouds are the highest level clouds and have a filmy, wispy and sometimes nervous or busy appearance. They are composed of ice crystals and when exposed to high velocity winds they have a striated appearance (Cloud 10). As the ice crystals fall they may encounter slower winds or winds of a different direction giving arise to curved lines or lines ending as hooks (mare’s tails or fallstreaks Cloud 11). Cirrus clouds are often the precursors of changing weather conditions.

During our time at the beach there were days where the sky appeared cloudless but the colour of the sky was a very hazy pale blue. Closer examination showed a very filmy layer of Cirrostratus cloud forming a uniform layer across the sky (Cloud 15).

Anyway get a copy of The Cloud Collector’s Handbook and use the Society’s cloud spotter’s scoring chart whenever you are out and about. You won’t regret it.

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