clouds – Forage France

29 March 202027 February 2022

Weather Predictions

Micro version of a longer article which can be found here.

Learn how to predict the weather using clouds, you can do this from a window or garden. have a go and see if you’re right!

Cirrus – is the most common high altitude cloud it is a sign of fair and pleasant weather to come.
Cirrostratus – A thin sheet like cloud that can cover the entire sky. It can be used to predict rain or snow if it’s cold enough within the next 12 – 24 hours.
Cirrocumulus – This cloud like the cirrostratus is a layer but differs because of its patchy appearance. When you see this cloud, it means that the weather is stable for now however it could be a prelude to stormy skies. If this cloud does precipitate it is rare that the droplets will reach the surface.
Altostratus – Forms ahead of a warm or occluded front. A warm front means light rain or snow and an occluded front is where a cold front and warm front have caught up with each other, joined together, which can cause strong winds and heavy rain. As the front passes Altostratus deepens and becomes Nimbostratus. Seeing this cloud can be an indicator that the weather is going to change for the worse.
Altocumulus – This cloud brings settled weather. If it does produce rain it is unlikely that the rain will reach the surface.
Stratus – If the weather is warmer it brings rain if it’s colder then it will bring snow. A low level grey blanket cloud that can sometimes be seen as fog.
Stratocumulus – Rarely produces rain. This cloud is usually seen at the tail end of bad weather, however can be a prelude to worse weather approaching.
Nimbostratus – Dark, low uniformly grey clouds. Widespread light to moderate precipitation. If you can see this one it’s probably already raining.
Cumulus – Fair weather cloud. A rounded top and a flat bottom this cloud means that it’s all going to be ok. However, this cloud can sometimes develop into Cumulonimbus which means you should probably think about heading indoors.
Cumulonimbus – Towering bad weather cloud with extreme weather, torrential rain, hail, lightning, but short lived so it’s not all that bad…

Using clouds to predict the weather is such an accessible activity to all people, you can even stay indoors or in your office if you like. Look out of the window, decide what type of cloud it is and see if your weather prediction comes true.

Have fun!

13 January 202027 February 2022

Stormy weather – how?

Whatever the weather we are not happy. Us Brits love moaning about the weather, too hot, too cold, too windy, too sunny, not sunny enough, haven’t had weather like this for ages, can’t wait for summer, this summer has been going on a bit long… you name it we bloody love moaning about it. On the Brink of storm Brian, Brin, Bertie or whatever significant storm is heading our way we ramp up the moaning and groaning, waiting, just waiting for the devastation after the storm, for it to never come, to only moan that the storm was not as powerful as predicted.

British pessimism aside, what are storms and why do we get them?

Names

Firstly, every year since 2015 the Met Office (Meteorological Office) releases the names of the storms for the coming year, the names of storms go from A-W. Leaving out Q, U, X, Y & Z because the U.S. Hurricane Centre finds it difficult to find names that start with those letters, so to keep consistency we followed suit.

This year in 2020 the names are Atiyah, Brendan, Ciara, Dennis, Ellen, Francis, Gerda, Hugh, Iris, Jan, Kitty, Liam, Maura, Noah, Olivia, Piet, Róisín, Samir, Tara, Vince & Willow

The more observant of you all will notice that the storms alternate boy and girl names, and interestingly the storms with girls names tend to cause more casualties. Scientists think that this is because female names are less threatening and people take less precautions ahead of and during the storm.

Not all storms get a name from the UK list, if the storm starts in another country like the U.S.A. then it keeps it’s name when it gets to the U.K. Not all storms get a name anyway, the only ones that do are thought to have the potential to cause significant damage. Usually when it is marked as ‘Amber’ be prepared, or ‘Red’ Take action.

You can take part in naming storms for the Met Office here.

Storms

A storm is created when low pressure forms within a system of high pressure – (low pressure spins clockwise & high pressure spins anticlockwise). Imagine this as wind. When the winds are travelling in opposite directions it can create clouds like cumulonimbus – see article on clouds – a storm cloud.

Winds

Wind is produced by the uneven temperature of the earth. Hot air rises as it rises the denser cold air rushes in to take its place. That air moving across the surface, we feel as wind. Wind is commonly measured in the Beaufort wind force scale of 0 – 12

Terminology for Wind & the Beaufort Scale

Calm – 0 – (1mph)
Light air – 1 – (1-3mph)
Breeze – 2,3,4,5 (4-24mph)
Squall – 6 (25-31mph gusts that last over 1 minute)
Gale – 7,8 & 9 (32-54mph)
Storm – 10 & 11 (55-72mph)
Hurricane – 12+ (73+mph)
Light air – 1 – (1-3mph)

Rain

Taken from – Weather predicting using clouds.

The tiny water droplets float around in the cloud and bump into each other sticking to each other, something we call cohesion. All this cohesion makes the water droplets larger and this means they are less able to fight the pull of gravity and when the pull is too much, they fall from the sky, creating rain. Rain drops can vary in mass from drizzle at 0.004mg and the largest during a storm at 300mg.

Lightning (and thunder)

Lightning is created when heavier (negatively) charged particles sink to the bottom of a cloud and the positively charged particles rise to the top. When there is a large build up of both it creates a spark, this is what we see as lightning and hear as thunder. We do not see and hear lightning at the same time because light travels much faster than sound.

Light travels at 299792458 meters per second and sound travels at 343 meters per second. If we round down sound to 333.3 meters per second that makes one second roughly 1Km away. Therefore if you count the seconds between seeing lightning and hearing it it will give you the approximate distance in Km – (seconds divided by 3). If you count multiple times and you are counting more seconds the storm is heading away from you, likewise the storm is getting closer if you count less seconds.

Mostly I hope you enjoy this years storms and have fun knowing a little more about the weather.

You can find out more from the Met Office.

16 December 201927 February 2022

Using clouds to predict the weather.

‘Looks like it’s going to rain, you should take a brolly’…

I believe that most people can subconsciously, and to some extent consciously, feel the change in the atmosphere as the sun closes its eyes and the dark clouds obscure it in the sky. The impending rain storm is coming.

Can we better predict what’s going to happen in the skies based on what we can see now? To answer that question we must first remind ourselves of the basics of clouds and what causes them to form in the first place.

What are clouds?

Clouds are the formation of water vapor that as it rises expands and cools. It then condenses to form what we see as clouds.

Each water droplet can vary in size from 1 – 100 microns (a human hair is 75 microns across) so very very small. That said the combined weight of all those water droplets means the average cumulus cloud weighs in at a whopping 1 million tonnes approximately. So how does it stay aloft i hear you ask? Well, the density of a cloud is around 1.003kg per m3 which makes it 0.4% lower than the surrounding air, making the cloud lighter allowing it to float.

What makes it rain?

What are the different types of clouds?

Clouds can be arranged into 3 broad categories, high, middle and low altitude clouds. High clouds form between 16000 and 43000 ft. Middle clouds form 6500 and 23000 ft and low clouds form below 6500 ft.

Now I’m not usually a fan of Latin names for objects when someone is trying to learn something new. After all the Maasai tribe of Kenya and northern Tanzania don’t know the latin names for all the animals and plants but have an exceptional knowledge of plants and wildlife that would put most of us to shame. In this case there aren’t really any common names for clouds so latin it is! It does not take too long to learn and actually follows a fairly straightforward pattern.

High level clouds are formed mainly of ice crystals due to the temperature and altitude in which they form. You can tell if the clouds are high altitude clouds as they do not obscure the sun (or make it opaque).

Cirrus – Means a ringlet or tuft.
Cirrostratus – Stratus means to flatten out or to be covered with a layer.
Cirrocumulus – Cumulus means accumulation or a heap/pile.

Middle level clouds are made up of water and sometimes, if it’s cold enough, ice. They quite often block out sunlight, but this is not a hard and fast rule.

Altostratus – Alto means height or upper air.
Altocumulus – Cumulus means accumulation or a heap/pile.

Low level clouds clouds tend to contain water, but can also be comprised of snow if the weather gets cold enough. Low clouds always block out sunlight.

Stratus – Saddle or Layer.
Stratocumulus – A layer of cumulus.
Nimbostratus – Nimbus means dark cloud or rain.
Cumulus – Accumulation.
Cumulonimbus – An accumulation of rain.

Right Latin lesson over, it’s all well and good knowing the name for something but what could it or does it mean? It’s really important to give name knowledge a purpose or what’s the point in learning the names for things?

Cirrus – is the most common high altitude cloud it is a sign of fair and pleasant weather to come.
Cirrostratus – A thin sheet like cloud that can cover the entire sky. It can be used to predict rain or snow if it’s cold enough within the next 12 – 24 hours.
Cirrocumulus – This cloud like the cirrostratus is a layer but differs because of its patchy appearance. When you see this cloud, it means that the weather is stable for now however it could be a prelude to stormy skies. If this cloud does precipitate it is rare that the droplets will reach the surface.
Altostratus – Forms ahead of a warm or occluded front. A warm front means light rain or snow and an occluded front is where a cold front and warm front have caught up with each other, joined together, which can cause strong winds and heavy rain. As the front passes Altostratus deepens and becomes Nimbostratus. Seeing this cloud can be an indicator that the weather is going to change for the worse.
Altocumulus – This cloud brings settled weather. If it does produce rain it is unlikely that the rain will reach the surface.
Stratus – If the weather is warmer it brings rain if it’s colder then it will bring snow. A low level grey blanket cloud that can sometimes be seen as fog.
Stratocumulus – Rarely produces rain. This cloud is usually seen at the tail end of bad weather, however can be a prelude to worse weather approaching.
Nimbostratus – Dark, low uniformly grey clouds. Widespread light to moderate precipitation. If you can see this one it’s probably already raining.
Cumulus – Fair weather cloud. A rounded top and a flat bottom this cloud means that it’s all going to be ok. However, this cloud can sometimes develop into Cumulonimbus which means you should probably think about heading indoors.
Cumulonimbus – Towering bad weather cloud with extreme weather, torrential rain, hail, lightning, but short lived so it’s not all that bad…

There are of course many types of clouds that fall in between these types and each can be affected by additional factors, temperature, wind direction and strength, atmospheric pressure. This article is designed to be a starting block for you to take some knowledge and develop it further.

If you want more information or have a question that needs answering. Please get in touch via social media or the website.

Remember to make time and connect with nature.

Tom