WTF Fun Fact 12978 – How Does Temperature Affect the Color of Leaves?

Have you noticed that autumn looks a bit different every year? Sometimes the leaves fall early. Other times they’re on the trees much longer to give a full display of color. A lot of this has to do with the temperature outside. But how does temperature affect the color of leaves?

The temperature of fall and its effect on leaves

As the nights get cooler in the northern hemisphere in September and October, we begin to see the trees change. If you’re lucky enough to live around a mixture of trees, you’ll begin to see bright red, orange, and yellow leaves appear.

Without as much daily sunlight, trees don’t go through as much photosynthesis. This is aprocess that produces sugars, which trees use as energy to grow and flower.

A reduction in photosynthesis leads to a reduction in chlorophyll as well, which is the pigment that makes leaves green. As they lose chlorophyll, they lose their green color and prepare to shed for the winter so trees can conserve their energy inside the branches and bark.

How does temperature affect the color of leaves?

But that still doesn’t explain the role of temperature.

The weather leading up to shorter days is actually quite important when it comes to determining how fall plays out for leaves .

We know that a reduction in chlorophyll leads to leaves being less green, but what makes some seasons produce more vibrant red leaves than others? Why does a tree turn bright orange one year and only a dull copper the next year?

Well, it turns out that the pigments that begin to show up once chlorophyll is reduced are dependent on both temperature and moisture conditions right before days start getting shorter. For example, some weather conditions make a leaf turn red early. It also helps it stay on the tree longer, so it goes through its full range of colors before falling off.

The role of weather in fall leaf displays

According to scientists at Michigan State (cited below), lots of warm days and cool nights narrow the veins in leaves. This helps trap the sugars made during photosynthesis in those leaves. When this happens, the sugars produce more vivid pigments.

“The most brilliant leaf displays follow a period of warm days filled with sunshine and cool nights. During this weather cycle, leaves produce an abundance of sugars during the sunny days. The cooler nights and gradual narrowing of leaf veins in the fall, means that a majority of the sugars produced are trapped in the leaf. An abundance of sugar and light in the leaf lead to the production of vivid anthocyanin pigments, which produce red, purple and crimson colors. Yellow and gold leaf colors are produced by carotenoid pigments, which are ever-present in the leaves and are therefore less dependent on the aforementioned conditions.”

Other factors in fall leaves

“Soil moisture also plays a role in the timing and brilliance of leaf color. The best displays are produced when the soil has been adequately moist throughout the year coupled with the aforementioned late summer weather. A late spring, or severe summer drought can delay the onset of color. A warm period during the fall can also decrease the intensity of fall colors by triggering early leaf drop before the colors have had a chance to develop.”

Finally, MSU explains that other factors can play a role in individual trees:

“Trees on the edge of low-lying areas, where cooler air collects at night, often display colors sooner than trees in an upland forested setting. Trees that are diseased or in decline may also display fall colors earlier than their healthy neighbors.

And that’s why no two autumns will ever look the same.  WTF fun facts

Source: “How weather affects fall colors” — Michigan State University Extension

WTF Fun Facts 12706 – Oxygen From The Ocean

It’s easy to think all our oxygen comes from trees on land – and a LOT of it does (especially rainforests, which there are lots of, and which need protection). But, in fact, most of it comes from the oceans.

That’s a bit harder to believe, but that doesn’t make it less true.

Plankton, specifically phytoplankton, produce most of the Earth’s oxygen. It also serves as food for sea creatures, but they don’t do much else that makes them interesting to most people. They just float around, completely at the mercy of the currents. They’re green and cruddy and you might even look at them and think “eww.”

And that’s fine since they also can’t be offended.

Here’s the deal: even though oceanic phytoplankton isn’t nearly as pretty as trees, it does similar work for us. These little organisms mostly float along the surface of the water or the upper part of the ocean where light still penetrates. They require sunlight to live and grow and produce food for other ocean creatures. They contain chlorophyll to capture the sunlight. If you remember back to grade school science, you probably see where this is going – photosynthesis.

Our oceanic phytoplankton turns the energy from sunlight, as well as carbon dioxide, and mineral salts partly into oxygen. There’s a lot of other stuff going on there too (other byproducts of photosynthesis, like the sugar they feed on), but oxygen is the byproduct we care about at the moment since we need it to breathe.

The cool thing is that even if you don’t live anywhere near an ocean, you still get the benefits because of the way the planet works. Oxygen is great because it just fills the atmosphere and doesn’t need to be shipped via trucks and planes to far-off destinations.

Scientists estimate that 50-80% of the oxygen production that takes place on Earth comes from the ocean. That’s a big range, but even if you go with the more conservative number, it’s clear that we can’t live without them. However, a lot of that oxygen also goes back into the ocean for other ocean life that needs it.

Don’t get us wrong, we love rainforests and regular trees too. But phytoplankton is doing more work than other flora when it comes to keeping breathing creatures alive.

We can do things like track plankton and get some readings off them, but it’s hard to know exact numbers of what they’re producing at any given time. The amount of oxygen they give off can change with the time of day or the time of year. It can also change depending on how healthy the oceans are.

One problem is that things like dead and decaying plants and animals in the ocean also consume oxygen when they decompose. That’s just one reason why killing off aquatic life (such as coral reefs) can be bad for us.

But if you remember one thing, it should be that these tiny, single-celled creatures do a lot of work for us by not only producing oxygen but by absorbing some of the CO2 we emit.

Some people call them “the lungs of the sea.” – WTF fun facts

Source: “How much oxygen comes from the ocean?” — National Oceanic and Atmospheric Administration