Pure water contains no impurities and freezes at 0°C. However, seawater – on average – contains 3.5 per cent of dissolved salts, which lowers the freezing point; this phenomenon is called freezing point depression. Freezing point depression is a colligative property of matter, which means it depends on the number of molecules present, not on the specific type of molecule or their mass (i.e. the dissolved substance doesn't have to be salt, but any soluble substance, it's the amount of dissolved molecules that is important). In terms ...

The titan arum (or stink plant) is an odd plant however you look at it. Known as the 'Corpse flower' in Indonesia, it's a colossal organism, the central column of 'spadix' growing up to three metres tall. The plant's corm – the underground root system where it stores food – is the largest in the world, the one at Kew Gardens weighing in at an astonishing 91kg when it was repotted last year. Once the flowers around it are ready for pollination, the spadix begins to generate the ...

Another fine edition of the best science monthly on the market hits newsstands today – get it now! From the performance-enhancing technology of the World Cup to the most unashamed luxury available on the planet's most expensive mega yachts, this issue will keep you distracted long after you were supposed to get back to work. But don't feel guilty; read on and feed your brain with fascinating facts on the wonder of twins, exploring below the surface of the oceans, creating the real Iron Man and the technologies capable of augmenting ...

Things are always cooler when slowed down, just ask John Woo. In that vein, check out this cool but also very funny video of a rather unfortunate chap being hit full in the face with a water balloon. This type of slow motion effect is achieved when each film frame is captured at a rate much faster than it will be played back, so when replayed at normal speed, ...

This is awesome! Check it out. The Golden Eagle has an average wingspan of over two metres and is one of the most well-recognised birds of prey on Earth. Their usual diet consists of smaller animals such as rabbits, marmots and squirrels, however, as you can see here, due to their huge size in advantageous circumstances they can take down much larger prey. Despite their numbers being ...

Issue 8 is another splendid feast for the mind, so read on to discover the highlights of this month's edition of your favourite science and technology magazine. First up is this month's rather swanky cover feature: Mega Yachts. You won't believe the high technology and advanced design of these masters of the seas. In this four-page extravaganza we look at the biggest and best the yachting industry has to offer, and we even knocked up a little brainstorm of what our ...

To answer this question there are two things which need to be considered – colour theory and refraction. Refraction is the change in direction of light as it goes from one material to another. It is due to a slight change in speed of the light and it explains why straws look bent in water. When light enters snow, it refracts. This is because snow is made from lots of ice crystals tightly packed together, the important fact here being that these crystals are translucent (light ...

The definition of an Indian summer is a period of mild sunny weather that is out of season. The term is commonly used to describe a sunny spell which can occur after the first frost. The first recorded usage of the term was in 1778, from a Frenchman who lived in America called John de Crevecoeur who mentioned it in a letter. The term had spread to Britain by the 19th Century. Indian summers are caused by stalled high pressure, this high pressure pushes air towards areas of ...

Check out this short clip from Simon Reeve's excellent BBC television series Tropic of Cancer. To see what it was like filming the third in his trilogy of round the world adventures, pick up the next issue of How It Works for a full interview.

These long white clouds you are referring to are called condensation trails or contrails. Jet fuel is made of carbon and hydrogen which burns in the presence of oxygen. In this reaction some of the carbon joins with the oxygen to make CO2 (carbon dioxide) and some of the hydrogen joins with the oxygen to make H2O (water). The water which comes out of the engine is invisible water vapour but as soon as it is exposed to the colder temperatures of the upper atmosphere, it condenses ...