Orbit: Episode Two

    The second instalment of the series follows the Earth's journey from the start of January to the Spring Equinox in March. Available on iplayer. What did you think?

    Kate begins the film on a day with a very significant point in our Earth's journey - Perihelion. Kate climbs Aonach Mor mountain, one of the highest mountains in Scotland, which brings her as close to the Sun as she'll ever be for the entire year.

    This however is not because of where she is but because of the point the Earth has reached in its orbit around the Sun. In fact we kick started our blog on this day just over a year ago, when we explored the elliptical shape of our planet's orbit and how significant this was to our understanding of Earth's climate.

    Later in the film Helen explains how the proximity of the Earth to the Sun doesn't guarantee warmth - which brings us to the tilt of the Earth (23.4 degrees) - a theme we explore in further detail in episode three.

    Throughout this episode Kate and Helen explore the increase in solar radiation and how land and ocean respond to it.

    Kate drives over a frozen lake in Canada with an ice road trucker in one of the coldest places in that region and learns how important this ice formation is to connecting communities.

    In this film we also tackle ice ages and how over time, as Earth has repeated it's annual journey, it's climate has changed.

    Helen dives under water in Belize to discover how sea levels have risen and fallen over time due to ice age - and explores the three cycles that need to be right in order for another ice age to exist.

    What did you think of episode two?

    (There are a total of three episodes in this series)

    Day 319: UK and world weather report

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    Dave Britton – Met Office | 14:00 PM, Tuesday, 15 November 2011

    Distance travelled ~ 819'651'200 km

    Last week was quiet week weather wise for the UK. Most of the country saw mainly cloudy, drizzly conditions with some mist and fog.

    Despite a few frosty mornings in the north west of Scotland, temperatures remained mild for the time of year. Double figure highs were reached every day and a maximum of temperature of 18.1 °C was recorded on Sunday at Otterbourne, near Winchester, Hampshire.

    Elsewhere in the world, flooding continues to cause havoc in Bangkok, where the death toll has now risen to over 500. The weather has started to ease after months of monsoon rain, but the volume of flood water is continuing to cause problems.

    Floods surround two industrial estates east of Bangkok

    Image credit: NASA

    Heavy rainfall has also affected Italy, where thousands were forced to evacuate around the River Po in Turin when water levels rose by 4 metres. Seven people are thought to have died as a result of the storms and torrential rain in the country.

    Over in North America, severe winter storms have hit both Canada and Alaska. In British Columbia a snow storm caused severe disruption to travel networks and power supplies, with ferries to Vancouver Island forced to stop sailing. Meanwhile, Alaska saw winds of up to 100mph combined with high seas and blizzard conditions. During the storm the rate of ice accretion - the process of ice building up on solid objects - was more than 15.6 inches an hour.

    The week ahead

    The UK:

    • The quiet weather is expected to continue with temperatures remaining generally around or slightly above normal throughout. However, there is the potential for some heavy rain and strong winds across north-western parts of the UK later in the week.

    Across Europe:

    • Low pressure over the eastern Mediterranean brings strong northeasterly winds through the Aegean Sea early in the week. Severe weather warnings have been in place for much of Greece, with storm force winds forecast in some areas. Although the strongest winds are likely to be on Monday, it will stay pretty breezy in the area for the next few days.

    • Bitterly cold weather continues in eastern Turkey, Armenia, Georgia and Azerbaijan, although temperatures should start to rise from Tuesday.

    Across the Americas:
    • Following the recent storms affecting the west coast of Alaska, the state is set to see temperatures falling dramatically over the next few days to be 10-15 °C below average by Friday. Night time lows of -35 °C look possible in places, with daytime temperatures at times not far above.

    • In South America there's heavy rain, strong winds and some relatively low temperatures for a time in southern Brazil at the start of this week, before the associated low pressure system moves east into the Atlantic around Tuesday.

    Across Africa:
    • The same eastern Mediterranean low pressure that brings strong winds to Greece is also causing lower than average temperatures over large parts of Egypt, mainly the north east, over the next few days, with above average winds and precipitation as well at first.

    Across Asia:
    • A spell of unsettled weather is forecast for the Philippines over the next few days. The system causing this will move into the South China Sea around mid-week and may later affect parts of southern China.

    • Some unseasonably low temperatures are expected in the Himalayas - Tibet, Bhutan and Nepal - with daytime temperatures at Lhasa, Tibet potentially around ten degrees below normal.

    A date with History: Fram polar expedition leaves Norway June 24 1893

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    Helen Czerski Helen Czerski | 16:30 PM, Friday, 24 June 2011

    Distance travelled ~ 450'240'000 km: day 175 

    Ice is an important contributor to our weather, but finding out about the Earth's ice was very hard work. It's still less than a hundred years since Amundsen first reached the South Pole (he arrived on the 14th of December 1911, beating Scott by 35 days). My favourite polar expedition is one that is rarely mentioned because it wasn't an expedition in the normal sense. It was made by a ship called the Fram, and there were no sleds or dogs, and there wasn't even any navigation. The Fram was designed to become a piece of pack ice, and it spent three whole years doing just that (from 1893-­‐1896). Its voyage was not only a fantastic oceanographic experiment but also an amazing illustration of the dynamic nature of the Arctic.



    We tend to think of polar ice as being a bit like giant dollops of whipped cream on top of a dessert, as smooth white splodges that from space almost look as though they're about the run down the sides of the Earth. 

    Ice at the South Pole is fairly static, but things are very different at the North Pole because the Arctic is an ocean, not a continent. In the Arctic ocean the ice is dense pack ice, always moving, breaking apart and reforming. Pushed by ocean currents below and by wind above, Arctic ice never gets to sit still. The ocean at the North Pole is about 4.2 km deep, and there's no flag there and no base because no piece of ice is ever over the North Pole for any length of time.

    Fridtjof Nansen designed the Fram to test the theory that there was an ocean current that crossed the entire Arctic basin. He reasoned that if the jostling ice chunks were pushed along from one side to the other, a ship could be pushed along too. It would be a bit like a conveyer belt to the North Pole, and all he would need was patience and the right ship. The danger was that the ship would be crushed by the huge slow-­‐moving pieces of ice, so the Fram was designed with a very round keel so that it would be lifted out of the water and carried rather than crushed. This plan worked beautifully, except that the Fram never quite got to the pole. The ship and her crew were pushed about all over the place [link to map], eventually drifting to the edge of the Arctic ocean and freedom after three years. The furthest north she reached was nearly 86 degrees, 280 miles from the pole.

    Even though she didn't get to the North Pole, the Fram clearly demonstrated the dynamic nature of ice in the Arctic, and we now know that individual pieces of ice can indeed travel from Siberia to Greenland in 3-­‐4 years, or can go round a sort of giant ice-­‐roundabout (called the Beaufort Gyre) in 7-­‐10 years. Most polar expedition stories are about humans struggling against natural forces to achieve their goal, but I like the Fram's exploits because they're about humans working with the enormous forces of this planet instead of against them. What are your favourite examples of that?

    Winter in Antarctica: how can ice keep the ocean warm?

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    Helen Czerski Helen Czerski | 15:45 PM, Monday, 16 May 2011

    Antarctic sea ice

    Image © NASA

    d ~ 349'900'800 km : day 136

    In Antarctica, it's getting colder. The sun last shone on the south pole in March, and the tilt of our planet means that each day complete darkness swallows up a bit more of the continent. Since there's no incoming energy from the sun, the land and the ocean can only cool down. And it's at this time of year in the south that an innocuous little fact, one that most of us take entirely for granted, quietly makes the huge Southern Ocean a much more hospitable place for almost all marine life.

    Ice floats. Icebergs, ice cubes, ice on a freezing river... they all float. And this is weird, because when most substances freeze they get more dense and so the bits that are frozen solid will sink to the bottom of the unfrozen liquid. Water has the quirk that when it freezes, the molecules form a rigid crystal structure with gaps between the atoms that weren't there before. The consequence is that ice is less dense than the water it froze from, and so it floats.

    If frozen water sank, just imagine what would happen. Ponds, lakes and the oceans would freeze from the bottom up. There would be nowhere warm and protected under the ice for living things to hide, and the water would just keep freezing upwards until there was no liquid left. All water-based life would have much more of a struggle to survive.

    As it is, ice actually acts as an insulating lid, keeping the water below it warm. Heat is lost from the liquid water surface about a hundred times faster than from the ice surface, so less heat is lost overall from an ice-covered ocean. At this time of year, sea ice is growing rapidly in the Antarctic, and it's as if the ocean is responding to the cold by growing itself a blanket. Every year in the Antarctic, 19 million square kilometers of sea ice is formed, and each summer almost all of it melts.

    This ice is also a bit like a floating pantry. Lots of algae and krill live on the bottom of it, and these are an important source of food for fish and other Antarctic life.

    Sea ice is amazing stuff. It's different to icebergs - those are huge lumps of ice that have fallen off glaciers into the ocean. Sea ice is the ocean freezing at its surface, thickening into large mobile slabs as the winter season goes on. My favourite thing about this ice is that even though the ocean is salty, sea ice isn't. As the water freezes, the salt molecules are squeezed out, first into little brine pockets and later (especially if the ice lasts more than one year) into the ocean. You could hack off a bit of multi-year sea ice, stick it in your drink and never notice its salty origins.

    So when you look at ice cubes jostling around in your glass this summer, think about the ice on the other side of the world, jostling around Antarctica in the dark. It's keeping a huge amount of extra heat in the Southern Ocean until the sun comes back, and all just because it floats.

    On the edge of the Arctic circle spring has us guessing

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    Stephen Marsh Stephen Marsh | 12:49 PM, Tuesday, 3 May 2011

    d ~ 316'454'400: day 123

    The 23 Degrees team are heading back out to Northern Canada on the edge of the Arctic Circle. The last time we were out there it was mid-winter and it was 35 degrees below zero. That's seriously cold. On that trip we were learning why Yellowknife was the coldest city in America, and why mid-January is the coldest period in the northern hemisphere. This time we are there to discover what happens when the Sun warming rays finally reach this northern territory.

    Frozen stream, northern territories

    For most of the northern hemisphere spring arrives gently, think of beautiful flowers blooming, blossom bursting, trees greening and animals starting to mate. But the 23 Degrees team are about to learn that up in the northern territories spring comes with a bang.

    We are travelling to the Hay River which flows towards the Great Slave Lake. During winter the Hay river is a major highway linking Yellowknife with the outside world. The frozen river becomes a three-lane highway for the ice road truckers to ship in supplies. But from April the days are getting longer and more and more solar energy is arriving, warming the ice. Now for most rivers this is not a big deal, the ice melts and the river flows. But not the Hay River because unusually it flows south to north, and that makes a big difference. Because of the planet's tilt the warming Sun's rays hit the headwaters of the river in the south first, while downstream in the north there's little sun so it stays really cold. This means that the upstream part of the river thaws first while the downstream section of the river stays frozen.

    Once the ice upstream melts and breaks up it starts to flow north towards the Great Slave Lake. When it gets there the great lumps of ice smash into the frozen lake - sometime creating huge pile-ups of ice. If these ice dams are big enough they can block off the flow of water, which then spreads into the surrounding tundra. That can be very bad news for the inhabitants of Hay River, the last time it happened the town was flooded.

    Kate Humble and the Team are going filming with scientists and local experts who are monitoring the break up of the ice in an attempt to see if there will be a flood. One indicator of how bad the ice break up is going to be is the Alexandra Falls. Right now the 35-metre waterfall is frozen solid but soon it's going to melt, with a serious crash.

    Hay river, northern territories

    In a brief moment hundreds of tonnes of ice will splinter and fall, and the whole waterfall will collapse. The incredible cascade of water and ice will only last for a short time but it signals the start of a tense period for the locals and the scientists. For the next few days they will closely monitor the ice break up to assess how much ice will hit the Slave Lake and how much flooding might occur.

    The 23 Degrees team will be there watching the break up and relaying back updates on this incredible spectacle.

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