You and I can't hear it - but scientists can. This is how it works, even though the Sun is 149, 000,000 kilometres [93,000,000 miles] from earth, surrounded by the vacuum of space which of course sound can't travel through, scientists can record vibrations from the Sun.
The entire Sun vibrates in a complex pattern of sound waves. Think of it like a giant bell. When you hit a bell, sound waves bounce back and forth inside the metal which makes its surface vibrate. If we had a super-powerful microscope we'd be able to see these patterns of vibrations on the surface.
Well scientists listening to the Sun at Stanford University aren't using a telescope. They are using an instrument called a Michelson Doppler Imager (MDI), which is on the SOHO spacecraft, orbiting the Sun 1,000,000 miles from Earth to record acoustic waves in the Sun.
Just like in the bell, the sound waves bounce from one side of the Sun to the other taking about two hours to cover the 1.4 million kilometers [ 870,000 miles]. When they hit the sides they cause the Sun's surface to oscillate.
The Sun's sound waves are at such a low frequency our ears can't hear them. So the scientists speed them up 42,000 times which compressed 40 days of recording vibrations into just a few seconds.
These sound waves are very important to scientist studying the Sun. because they travel underneath the Sun's surface and are affected by what's going on inside the Sun. So scientists can use the oscillations to learn about how the structure of the Sun's interior and how it shapes its surface.
The sun - that giant ball of boiling gravity-driven nuclear reaction - has been blasting us with electromagnetic radiation for billions of years. "Radiation" is a word loaded with bad connotations, but actually we live surrounded by it and depending on it every day. We can see and feel some of that radiation - yet our eyes and skin experience only a very small range of the sun's rays down here in the murky depths of our atmosphere.
Electromagnetic radiation travels from the sun as waves and there's a whole spectrum of wavelengths, going from nano-meters short to kilometers long. Each wavelength totally changes how we experience that radiation and what we call it. The smallest waves we get from the sun are x-rays, which are small and energetic enough to pass through your flesh but not quite through your bones. A little larger than x-rays are ultraviolet rays which we know from all the professional advice on sun-blocking creams can be damaging to your skin cells. Next up we have our good friend visible light, followed by infrared. Microwaves are the next biggest and finally we come to radio waves - a really broad category with wavelengths up to tens of kilometers long.
Why, bathed in all this variety, have our eyes developed to see only visible light? Just as objects around us are coloured because their molecules absorb or scatter certain wavelengths of light, different particles and molecules in the atmosphere also do the same. We don't see this because visible light lies in what is called an "atmospheric window" - it can travel relatively freely through the atmosphere without being absorbed or scattered along the way. Having said that visible light doesn't pass through all atmospheric objects easily; water droplets are particularly good at scattering visible light, which is why we can see clouds. But if our eyes were tuned to a wavelength which was not in an atmospheric window, we would just be surrounded by a permanent fog of light scattered by the atmosphere. And that would be pretty useless for getting around.
There are other atmospheric windows, though and you might wonder why we haven't chosen one of these? Light travels easily in the "middle infrared" for example - the wavelength of heat. If we could tune our eyes to see in this window then we would live in a dimmer world where warm things shine in their own light. Without temperature contrasts, objects of the same temperature would tend to blend into one and cold-blooded animals like snakes or crocodiles may well be perfectly camouflaged. There is also a third major atmospheric window at the wavelength of radio waves, which is why we use this for communicating. If our eyes saw through this window then we would see an alien world - lit up by a dim sun, radio transmitters and the odd pulsar.
We use the visible because here the sun is at its brightest and it is brighter than anything else on Earth or in the sky. This gives us the best chance of seeing our landscape clearly. We can walk around our world safely, avoiding objects as visible light is scattered off them. And this means that - among other things - we can devote a bit more time to enjoying the beauty of light and the things it allows us to see.
Weather forecasting has made amazing progress in the past century. The days of relying on fir cones, star-gazing, folk sayings or supersized rodents are long gone. But how much better can it get? Will we ever know for sure that it'll be sunny three weeks from Tuesday?
To answer this, we first need to know a little about how weather forecasting works. What we call "weather" is just a description of what our atmosphere is up to - how hot the air is, how dense it is, what direction it's moving in and whether or not it's carrying much water with it. What weather forecasters do comes in two stages. First of all, they collect as much weather data (temperature, pressure, wind speed and so on) as they can from as many places as possible, to build up a picture of the weather right at this moment. This stage is generally automated, since there are lots of weather stations and satellites out there continually making measurements. Then, the forecasters use the laws of physics and a very large computer to work out how all that weather will have changed a minute from now, and then a minute after that. And so they step forward in time, using the answer from each step to work out the answer for the next step. So far, so good. To have perfect weather forecasts, all we need are amazingly powerful computers, and perfect information about what's happening now, right?
Sadly, no. Weather is an example of a chaotic system, and "chaos" here has a precise scientific meaning. What it means for weather is that however perfect our calculations are, there is no single answer about what will happen a month from now. This is because of the "butterfly effect" - tiny differences in the starting information can grow in importance as time goes on. Although this was only scientifically described in 1963, the concept isn't new. Do you remember this proverb?
For want of a nail the shoe was lost;
For want of a shoe the horse was lost;
For want of a horse the battle was lost;
For the failure of battle the kingdom was lost--
All for the want of a horse-shoe nail
This verse has been around for at least 500 years, and it's basically a description of a chaotic system. A single nail turns out to have a massive influence, but there was no way of knowing that beforehand.
We have all heard that a butterfly flapping its wings in Brazil could cause a tornado in Texas. But there isn't just one mischief-making butterfly out there. There are billions, and they've all got four wings each. And then you've got the ladybirds, the sparrows on the roof, my cousin's chickens and all the paper aeroplanes in the world. And you - don't touch that coffee! You might cause a tornado in Torquay.
The serious point here is that there is no way of measuring and including all of the tiny effects that everyday life has, or of knowing which ones will turn out to be the important ones. 10-14 days is about the length of time that it takes for some of those tiny effects to turn into much larger ones, so there is no way to predict the exact weather further ahead than that. We can still get the probabilities right - a 50% chance of a sunny day, for example. This is why medium-range and long-range forecasting is worth doing. But for exact prediction, 10-14 days is the limit and we're stuck with it.
That's fine by me though. I think that exact weather predictions months ahead would make life terribly dull. Hooray for chaos!
Are we now in spring? Well the date of spring equinox has now passed and I think it's safe to say spring has well and truly arrived in the northern hemisphere. With this increase solar energy comes the rebirth of nature and dare I say summer - perhaps too soon to be getting excited, but it's inevitable so why not.
We launched our 23 Degrees Flickr pool with the spring equinox and we are thankful for the great photos that now form part of it. Now, as promised we have put together the best photos that were taken on 20th/21st March to mark the last day of winter and first day of spring. Enjoy!
The 2011 spring equinox in the northern hemisphere occurs Sunday, March 20, 23:21 Universal Time (GMT), the time reference based on the rotation of the earth compared to distant celestial objects (Translate Universal time to my time).
Image courtesy of NASA
For the Spring Equinox Kate Humble and the team have been encouraging you to get the camera ready for the ultimate photo challenge. Send us your photos of sunrise or photos of spring bursting forth where-ever you are. It could be flowers blooming, a beautiful shot of the sun rising or a celebration at an ancient monument like Stonehenge - whatever it is we want to know about it. We'll use the best photos of the 20th/21st March to build a photo montage of the Equinox experience.
Just to give you an idea on the 20th March (UK England) the Sun will rise at 06:04 and set at 18:13 and on 21st March which will see the "first sunrise of Spring" the Sun will rise (UK England) at 06:02 and set at 18:15 (Times the Sun will rise and set where I am).
You can send us your photos by email or add your photos to the BBC 23 Degrees Flickr pool. Wishing everyone a great spring equinox!
We're coming up to the spring equinox, the official start of spring for many people, and it really feels to me like the seasons are changing.The seasons on earth are, of course, the result of the 23 degree tilt in our axis of rotation.
But what might our world be like without that tilt, and without its changing seasons? We wouldn't experience the usual swings between summer and winter, obviously, but would we have a permanent spring or autumn climate, or might the lack of axial tilt have different implications for our environment?
The earth hasn't always rotated with a 23 degree tilt. Pretty much nothing about the Earth's climate stays constant if you wait long enough, and that tilt is no exception. It wobbles up and down by a couple of degrees every 41,000 years or so (at the moment the tilt is slowly decreasing), and the strength of the seasons the earth experiences changes with it. When the tilt is greater, summers are warmer and winters are colder, and when the tilt is smaller there's less of a difference in the seasons. These repeating cycles in the strength of the seasons probably play an important role in forcing the huge climate shifts of the glacial cycles that the earth has experienced over the last million years - and that's all with changes of just 2 or 3 degrees in the tilt.
For fun, I set up a relatively simple model to simulate what the climate on an earth with a 0 degree tilt might be like. There are a few details that make this more of a toy than a serious scientific study, but we can still use it to illustrate some of the things that could happen in a 0 degree world. To start with, of course, the seasons disappear: although the weather is still different from day to day, February is much the same as June and October. However, if you guessed that the earth's climate in a 0 degree tilt world would permanently be stuck halfway between our usual summer and winter, you'd be wrong!
Images courtesy of Dr Robin Smith/University of Reading
A good way of imagining what it would be like to live on the 0 degree tilt world is to see how the ecosystems that we know from our 23 degree world would fare if we and they moved there*. The top panel shows a very simple way to characterise the climate of our 23 degree world in this kind of scheme. Greens show areas predominantly suitable for types of forest, browns are drier areas and grasslands, with grey for tundra, yellow for deserts and barren areas and ice caps in blue. There's a lot of fertile vegetation in this view of our world, with some desert in the hotter, drier areas and tundra and polar ice right up in the north.
The bottom panel shows what our toy simulation of a 0 degree world looks like. This climate is much less suited to our usual types of vegetation, with much larger barren desert areas, and a huge expansion of polar ice over Asia and North America. The
area suitable for vegetation at in the northern hemisphere shrinks dramatically, and northern Europe swaps its forests for tundra. The average temperature here in Britain sinks to a cool 7 degree C all year round, only varying by a couple of degrees warmer or cooler at most. Not everything would change for us, though - we'd still get about as much rain every year in a 0 degree tilt climate as we do now.
So, the earth's 23 degree tilt doesn't just give us the variations of the seasons and all the wonderful things we'll be seeing from this series - it's really important for setting the basic foundations of the environment we take for granted in our part of the world. As you can see, we'd have a very different planet without those 23 degrees.
Dr Robin Smith NCAS-Climate Dept. of Meteorology, University of Reading
* if the earth really had a non-seasonal climate, totally different types of vegetation would certainly evolve, so this is just a simple way of visualising what the different climates would be like.
The 23 Degrees team are on their way to Chichen Itza in the Yucatan region of Mexico to film the Spring Equinox.
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Chichen Itza is one of the great archaeological sites of the New World and was built around 1500 years ago by the Maya civilisation. At its peak, in the 10th century AD it was a thriving city that sprawled over 25 square kilometres and was home to more than 40000 people. Now much of the city has been re-claimed by jungle, but its central complex of temples remains. The site is split up into groups of buildings, connected by a network of roads that were once paved. The main three groups are the Great North Platform that includes El Castillo also know as the temple of Kukulkan [the Maya name for Quetzalcoatl] , the Temple of Warriors and the Great Ball Court; The Ossario Group, which includes the Temple of Xtoloc; and the Central Group, which includes the Caracol, Las Monjas, and Akab Dzib.
The Maya created these extraordinary structures to track the sun’s passage across the sky because they like many ancient civilisations worshipped the sun as a god. They believed that their kings were descended from it. But their relationship with the sun was more than just kinship, it delved into the meaning of time and life itself. The Mayan symbol for the Sun called K’in had several meanings. It could stand for just the sun, but also the sun god. But that’s not all; this symbol implies that the Maya had a more profound understanding of their existence because K’in could also mean day and time. A symbol that links the sun, with day and time suggests that the Maya may have thought of time as a real entity linked to the sun’s passage across the sky. Perhaps they had realised that life came from the intricate relationship between earth, the sun and time itself.
The focus of our filming will be the temple of Kukulkan. It is a powerful symbol of the Maya’s understanding of our planets intimate relationship with the sun. The pyramid has 4 sets of steps, one on each side. Each has 91 steps which added together make 364. Leading up to the platform at the top is one final step, making a total of 365 steps. A coincidence; I don’t think so. The Maya were great astronomers who had developed a profound understanding of our orbit. That’s not all the Temple of Kukulkan is aligned so that on the Equinox the Sun’s rays cast a shadow down the corner of the structure in the shape of a plumed serpent, Kukulkan the Maya feathered serpent who was a divine messenger between the gods and man. As the sun moves across the sky, the shadows from the corner tiers slither down the northern side of the pyramid to the serpent's head at the base.
To capture this moment 23 Degrees team are using a range of techniques including HD time lapse , aerial shots using a gyroscopically stabilised camera in a helicopter and HD footage on the ground. Hopefully using our 21st technology we can capture an event devised by the imagination and engineering of ancient astronomers many thousands of years ago.
Let us know of celebrations happening in the UK and around the world, email us, add your photos to our Flickr pool or put #myequinox in your tweets.
The short answer to this is yes. But the effects of such a shift are tiny. The Earth's tilt and rotational spin on its axis as it travels around the Sun causes our seasons. The earthquake in Japan moved the axis of rotation by around 16 cm. That might sound like a lot, but it's small compared to the size of the Earth. 1 degree change to the tilt of the axis of the Earth would mean moving it by around 110 km.
But the quake's interference with our axis doesn't stop there. The Japanese landmass was moved around by as much as 4m. This redistribution of mass on the surface changes our moment of inertia. In order to conserve angular momentum, the changes in inertia are compensated by changes in the rate of rotation of the Earth about the axis. After the earthquake it's quite possible that our days will be 1.8 millionths of a second shorter because of this shifting.
We can see differences in the average length of the day due to other changes in the Earth and atmosphere. The plots below show that there is a significant seasonal variation, with the day length (speed of rotation) being shortest (fastest) during the boreal summer. This happens because the northern hemisphere winds slow down in the summer and the momentum they lose - half the momentum of the atmosphere - is transferred to the Earth. This increase in momentum makes the Earth spin faster and our days become slightly shorter by 1-2 milliseconds.
So while the changes brought to our planet by the earthquake are unique and collosal enough to affect the Earth; they aren't big enough that we will notice them any more than we notice the milliseconds we lose each summer.
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Read Series Producer Stephen Marsh's post on solar energy and sea ice to find out more about the teams' mission a couple of days ago in Kulusuk on the east coast of Greenland.
On our annual journey around the Sun we are approaching a particular significant day: March 20th known as the Vernal or Spring Equinox. For many of us who live in cities, largely divorced from nature this day may have little significance. But for those who are still attuned to the changing seasons, the spring equinox is an important time in our relationship with the Sun.
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Equinox means 'equal night' in Latin. On this day the hours of light and darkness are of equal length, so wherever you are on the planet you will get 12 hours of day and 12 hours of night. But it's also a moment of change. On the day of the equinox the planet is in a sense in "neutral", each hemisphere poised at the mid point of its journey between summer and winter - at least in terms of solar radiation. But then the Earth shifts slightly further around the sun, and everything changes. In the northern hemisphere that means longer and longer days and more and more solar energy. Meanwhile the southern hemisphere will face shorter and shorter days, beginning its descent into winter.
For centuries the equinox has been a time of celebration.
In the UK, Druids will gather at Stonehenge. They come to celebrate the ancient Saxon goddess Eostre who represents new beginnings and fertility.
In Japan they mark the equinox with Shunbun No Hi a traditional holiday to mark the arrival of spring. They eat the "nightingale cake" made from sticky rice filled with a sweet white bean paste.
The festival of Nowruz which is Farsi for "new year" has been celebrated for over 3,000 years. It originated in ancient Persia, now modern day Iran, as the Zoroastrian New Year. It signifies the renewal of nature and life itself and is celebrated by the purification rite of fire jumping. The ashes from the fire - which represent the hardships of the previous year - are thrown away, to banish the hardships of the winter.
In Poland they celebrate the spring equinox by burning an effigy of Marzanna - a goddess associated with winter - and then drowning it. By destroying the winter goddess, the people put the long, dark days of winter behind them and welcome the warmth and light of spring.
The 23 Degrees team will experience the equinox at Chichen Itza in the Yucatan region of Mexico. Along with around 60,000 modern day pilgrims we'll watch the sun rise at the temple of Kukalcan. The temple is specifically designed to mark the equinox. It is perfectly aligned so that on this particular day the Sun's rays cast a shadow down the pyramid stairs. This shadow creates the body of a snake, Kukulcan, the Maya feathered serpent who was a divine messenger between Gods and man.
The 23 Degrees team would love to hear and see where you celebrate the equinox, whether it's in the city, in the country, in fact anywhere on the planet. If you take photos of equinox celebrations why not add it to the BBC 23 Degrees pool and email us your videos - it could even be a photo of the sun rising on the morning of equinox where ever you are. Let's build a global picture!
Earth's relationship with the Sun is of huge significance to the 23 Degrees team. Its 23.5 degree tilt is what makes our planet's annual journey around the Sun interesting and it's why we're encouraging everyone to help us record that journey. But maybe it's time we also looked up at the moon. Our planet's relationship with the Moon also plays a part in the Earth's cycle and the passing of time - the moon goes around the Earth and the Earth goes around the Sun which goes around the galaxy. It almost sounds like the solar system runs like clockwork right? But maybe it should be the other way around. Clocks run like the solar system. Our Sun dominates our concept of time but the moon is 400 times closer to us than the Sun is, and it moves around our planet steadily like the hand of a clock. Could we use the moon to tell the time if we wanted to?
It's tricky because the moon orbits Earth at a fixed rate but that rate has nothing to do with how fast the Earth spins or how fast the Earth goes around the sun. Inconveniently the numbers don't divide cleanly. However, during any single day the position of the moon doesn't change very much so it's quite a good reference point. Once the sun has set you're on the side of the Earth facing away from the sun slowly spinning back towards sunlight. If you know where you are on that journey you know the time. Here are some ways that the moon can help.
The ocean bulges out towards the moon attracted by its gravity. As the Earth spins we pass through the bulge and out the other side. We call that bulge a tide. If you're by the beach on a cloudy night you can get an idea of the time just by watching the tide level. In most places high tide is six hours after low tide, and you can use this even if you can't see the moon directly.
The moon's gravity doesn't only affect the water. It's also tugging on us, and if the moon is overhead pulling us upwards, it balances out a little bit of Earth's gravity pulling us downwards. If you stood on some very sensitive scales at a full moon, you'd notice that you weighed about a quarter of a gram less at midnight than you did at midday. So you could tell the time by monitoring how your weight changed during the night. It's not a very useful clock - you'd have to weigh anything you ate or drank and not put any extra clothes on. But in theory you could use your weight as a clock, because it changes systematically as you rotate closer to and further away from the moon. You have your own tide.
At full moon a normal sundial can be used as a moon dial. The moon is more or less exactly where the sun would be in the sky during daytime, except that the times on the sundial will be 12 hours too early. And of course, if you can see the moon, you can watch its progress across the sky and estimate the time in the same way that you would with the sun.
But why expend all this effort to help the moon tell solar time? The moon has its own time, and there's a tide-powered clock in London to tell you what that is. The Aluna clock is at Trinity Buoy Wharf in London - a prototype for a larger one to be built next year. I love this idea because the progress of the sun going across the sky is only one way of keeping track of time. Everything in the universe with an orbit is like the hand of a different clock all measuring the same time in different units. The moon is just one clock of many!
Kate Humble and the 23 Degrees team are in Kulusuk on the east coast of Greenland. Their mission is to travel out to the very edge of the Arctic sea ice. If we're lucky their arrival will coincide with a critical moment in the annual cycle of the sea ice.
They will be taken onto the ice by Inuit hunters from the village. The beginning of March is an important time for the seal hunters. The long winter nights are over, the days are getting longer, and the increasing sunlight attracts seals onto the sea ice to moult their winter coat. The sea ice allows the hunters to travel quickly over great distances to find the seals.
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What's remarkable about the sea ice is how late in the year it melts. Records of the extent of the sea ice over the last 50 years show that on average it reaches its maximum in early March, more than two months after the winter solstice when the northern hemisphere received the least amount of sunlight. So the team are hoping to be on the ice at the tipping point - the moment when the sea ice is neither expanding nor contracting. They're going to discover why there's such a big lag between increasing solar radiation and the melting of the sea ice
The reason for this lag is the relationship between air temperature and the thermal properties of water. The ocean has huge thermal inertia - it takes a long time to cool down and a long time to heat up. Air on the other hand responds quickly to solar energy. So at this time of year the air is starting to warm up as solar radiation increases. But critically, it's not yet warmed enough to get above freezing. The sea on the other hand is still cooling down; the air temperature is still below freezing, so the ocean continues to lose heat. This process continues into March until the air temperature rises above freezing. Now the sea can start to warm up, the sea ice advance is halted, and gradually the process goes into reverse.
Early surveys of the ice for 2011 suggest that the extent of sea ice this year has been the smallest in living memory. There has been a particularly warm winter in Greenland so the seas haven't cooled down as much as normal. Scientists believe it is part of a trend linked to Global Warming. There have been significant annual variations, but the trend seems to be that the extent of the sea ice has been getting smaller for around ten years. It's also been getting thinner, which is not good news for the hunters of Kulusuk, because without the sea ice, hunting is a lot more difficult.
In a few weeks, the planet's tilt will bring even more solar energy to the Arctic, and the sea ice will finally begin to melt and recede. The ebb and flow of the sea ice here in Greenland reveals the extraordinary complexity of our planet's response to the energy it gets from the sun. It's a fascinating relationship, and one that determines the fate of all life on earth.
Today is St David's day. A day for celebrating all things connected to Welsh life and culture - eisteddfod, rugby and mountains to name the most obvious. But there is another aspect to Wales that we could well be celebrating.
Not many countries could be said to have a national weather-type but certainly for people journeying from the south of England the weather type culturally associated with Wales is rain. Rainwater seeps down the mountainsides and gushes along rocky stream beds watering lush grasses on steep slopes and down into fertile mountain valleys.
But why so much rain? Well it's caused by the mountains themselves. They act as a physical barrier to the prevailing westerly wind and air is forced upwards over the craggy peaks. High up there temperatures are cooler and so water vapour in the air condenses turning from an invisible gas into millions of droplets of liquid water or clouds. As more and more water condenses the droplets become bigger and heavier and often will eventually fall out of the cloud as rain.
But why do many holiday makers from the east find this Welsh rainfall so particularly unpleasant? That's all to do with typical weather in the east. After this air has passed over the mountains it descends again and moves towards the east of the country. But even though clouds may form it's much less likely that rain will fall now - like wringing out a sponge the journey up over the mountains has dried out the air and there simply isn't enough water left in it to give the same amounts of rain. Land which lies downwind of mountains like these is said to be in their "rain shadow". London lies in the rain shadow of the Welsh mountains so the wet welsh weather actually keeps our capital dry - drier than Rome in fact.
Every day is different of course but this is the typical setup of rain over the southern half of UK brought about because of our landscape. Even smaller-scale variations in geography across the country can lead to localised tendencies in the weather called "microclimates". The particular location of a hill may mean that one town is often flooded and rainy while another is usually dry. These microclimates exist all over the UK.
So if you're considering enjoying some lavabread or barabrith tonight then take a few moments to think about whether you yourself live in a microclimate and what the cause of your local climate may be. If there was ever a day for celebrating our glorious tapestry of regional weather variations (and that life-giving rain in particular) then St David's day could well be it.
During February, the longest winter nights have passed in the northern hemisphere for another year as the day length increases ahead of next months equinox.
Meteorologically, spring begins on 1st March and ends on 31st May, which is for statistical purposes and historical records. For many people the season changeover is when the oscillating date of the spring equinox occurs, which this year is 20th March.
Although spring can be determined by calendar dates, the natural variability within the atmosphere means that, as far as the weather is concerned, year to year differences vary widely. These changeable weather patterns can have big impacts on how flora and fauna respond through the season.
The increasing height of the Sun above the horizon by day gradually brings increasing warmth to the ground and the first signs of spring begin to appear as nature wakes up. However, the influence of the Sun is fairly limited early in spring.
Following the winter months, the ground has been able to cool down and it takes time for solar radiation to warm it once more. This is because air is a poor conductor of heat, so the Sun's energy is not entirely absorbed by the ground to warm it up. This leads to a delay in air temperatures increasing through the spring.
This can be illustrated when comparing the 30 year UK mean temperature for the equinox months of March and September, which effectively receive a similar amount of solar radiation. In March, the figure is 5.2 Celsius, however, in September the value is more than double at 12.3 Celsius.
In addition to day length increasing, different types of weather patterns have a big effect on how quickly the ground warms. These in turn have a direct impact on the plant and animal worlds.
Of all the seasons, some of the biggest differences between day and night temperatures occur during spring. As early as March, maximum temperatures can exceed 20 Celsius, especially in southern parts off the UK, and in May they can reach more than 30 Celsius.
In sheltered areas throughout the season, minimum temperatures can fall well below freezing and as low as minus 10 early on. Snow will be a regular feature across many parts in the first half of the season. In fact statistics show that snow is more likely to fall at Easter than at Christmas.
Looking beyond the year to year differences we see that our climate is changing. For many the first evidence of this can already be seen in gardens across the UK. Seasons are already changing with spring having advanced 2-6 days per decade in the UK. Those with gardens need to start cutting their lawns almost two weeks earlier than they did in 2001.
Research undertaken by the Met Office Hadley Centre has also confirmed that the growing season of plants is likely to increase by around 40 days by 2080, due to the earlier start to spring and later end to autumn.
Orbit: Earth's Extraordinary Journey explores the relationship between the Earth's orbit and the weather. Previously '23 Degrees' (working title); on this blog the weather community were invited to discuss their experiences of severe weather as and when events developed and share their iwitness footage throughout 2011. The audience were provided with an insight to the making of the series and exclusive behind the scenes footage. Follow us on Twitter.
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| 13:00 PM, Thursday, 31 March 2011
Kate Humble:
Helen Czerski:
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