Joseph03

So what's happening is that as skis move,they rub the surface of the snow and warm it up,creating a thin layer of water,which helps them slide along.So technically, it's not really snow skiing,but water skiing.But it is true that no matter how hard you look,you're almost definitely not going to find two identical snowflakes,and that's a mystery that scientists are still trying to solve,though we know that it has to do with the many possible branching points in snowflake formation,and the differences in temperature and humidity,and while we wait for the answer,we can enjoy watching these tiny fractals falling from the sky.

Weather conditions affect snow on the ground, as well.Warmer ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes stick to each other.Melted snow also plays a critical role in another wintry activity, skiing.Completely dry snow is very difficult to ski on because there's too much friction between the jagged snowflakes and the ski surface.

As a snowflake falls,changes in weather conditions can affect how it grows,and even small differences in the paths two snowflakes take will differentiate their shapes.However, since conditions at the six sharp edges of one snowflake are similar,a symmetric snowflake can grow.

When water freezes, this bonding occurs on repeat,ultimately forming a hexagonal structure due to the angle between hydrogens and oxygen within each molecule.This is the seed of a snowflake,and it retains a hexagonal shape as it grows.As the snowflake moves through the air,water vapor molecules stick to the six sharp edges and expand the snowflake outwards, bit by bit.A snowflake's developing shape depends on atmospheric conditions,like humidity and temperature.

The water molecule as a whole is electrically neutral,but oxygen gets a larger share of electrons,making it slightly negative and the hydrogens slightly positive.Due to its negative charge,the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule.And so a weak bond between the two molecules,called a hydrogen bond,is formed.

Similar charges repel,so they tend to stay as far away from each other as possible.The pairs form four electron clouds,two of which are where the hydrogen and oxygen share electrons.The repulsion between the unbonded pairs is even stronger than repulsion between the shared pairs,so the two hydrogens get pushed a little further to an angle of 104.5 degrees.

The two electrons from oxygen's outer shell are shared with two electrons from both hydrogens as they bond together,and the remaining four outer shell electrons from oxygen form two pairs.We call the bonds between these atoms covalent bonds.The pairs of electrons are all negatively charged.

But that still doesn't explain why snowflakes have six sides.To understand that,we need to delve deeper into the physics of water.Water is made out of two hydrogen atoms and one oxygen atom.A single water molecule thus has ten protons and ten electrons,eight from oxygen and one from each hydrogen atom.

If you ever find yourself gazing at falling snow,why not catch a few snowflakes on your glove and examine their shapes?You might notice that they look symmetrical,and if you look closely,you'll see they have six sides.You could say a snowflake is simply frozen water,but compare one with an ice cube from the freezer,and you'll realize they're very different things.Unlike ice cubes, formed when liquid freezes into a solid,snowflakes form when water vapor turns straight into ice.

Through the mycorrhizae, trees can tell when nutrients or signaling molecules are coming from a member of their own species or not.They can even tell when information is coming from a close relative like a sibling or parent.Trees can also share information about events like drought or insect attacks through their fungal networks,causing their neighbors to increase production of protective enzymes in anticipation of threats.The forest’s health relies on these intricate communications and exchanges.With everything so deeply interconnected,what impacts one species is bound to impact others.

But why does fungus transport resources from tree to tree?This is one of the mysteries of the mycorrhizal networks.It makes sense for fungus to exchange soil nutrients and sugar with a tree—both parties benefit.The fungus likely benefits in less obvious ways from being part of a network between trees, but the exact ways aren’t totally clear.Maybe the fungus benefits from having connections with as many different trees as possible,and maximizes its connections by shuttling molecules between trees.Or maybe plants reduce their contributions to fungi if the fungi don’t facilitate exchanges between trees.Whatever the reasons,these fungi pass an incredible amount of information between trees.

That means that the sugars flow from the tree roots into the fungal hyphae.Once the sugars enter the fungus,they travel along the hyphae through pores between cells or through special hollow transporter hyphae.The fungus absorbs some of the sugars,but some travels on and enters the roots of a neighboring tree,a seedling that grows in the shade and has less opportunity to photosynthesize sugars.

From there, sugar flows down to the roots.Mycorrhizal fungi encounter the tips of the roots and either surround or penetrate the outer root cells,depending on the type of fungi.Fungi cannot produce sugars, though they need them for fuel just like trees do.They can, however,collect nutrients from the soil much more efficiently than tree roots—and pass these nutrients into the tree roots.In general,substances flow from where they are more abundant to where they are less abundant,or from source to sink.

To get a sense of how substances flow through this network,let’s zoom in on sugars,as they travel from a mature tree to a neighboring seedling.Sugar’s journey starts high above the ground,in the leaves of the tallest trees above the canopy.The leaves use the ample sunlight up there to create sugars through photosynthesis.This essential fuel then travels through the tree to the base of the trunk in the thick sap.

We know the oldest trees have the largest mycorrhizal networks with the most connections to other trees,but these connections are incredibly complicated to trace.That’s because there are about a hundred species of mycorrhizal fungi–and an individual tree might be colonized by dozens of different fungal organisms,each of which connects to a unique set of other trees,which in turn each have their own unique set of fungal associations.

Partnering with these roots are symbiotic fungi called mycorrhizae.These fungi have countless branching, thread-like hyphae that together make up the mycelium.The mycelium spreads across a much larger area than the tree root systemand connect the roots of different trees together.These connections form mycorrhizal networks.Through mycorrhizal networks,fungi can pass resources and signaling molecules between trees.

Most of the forest lives in the shadow of the giantsthat make up the highest canopy.These are the oldest trees,with hundreds of children and thousands of grandchildren.They check in with their neighbors, sharing food, supplies,and wisdom gained over their long lives.They do all this rooted in place, unable to speak, reach out, or move around.The secret to their success lies under the forest floor,where vast root systems support the towering trunks above.