I Scream, You Scream, We All Scream for Isoprene

Plants are well known for absorbing carbon dioxide from the atmosphere and replacing it with oxygen as part of the photosynthesis process. But that’s not the only thing they put into the air. Trees emit tons of a chemical known as isoprene every year, mostly during summer months. It’s surprising to learn that plants contribute to air pollution. 

An abundance of isoprene can lead to formation of greater amounts of ozone by combining with nitrogen in the form of NO and NO2. Ozone in higher levels of the atmosphere is good because it blocks harmful UV rays from the sun, but at our level it’s a major pollutant.  

The current theory is that plants produce isoprene as a method of heat resistance. Like water vapor and oxygen, it is emitted through the pores in a plant’s leaf. Not every plant produces isoprene, but the biggest producers in the US are oaks and poplars.  

Shenandoah National Park (NPS)

Isoprene is what gives the Blue Ridge Mountains their blue appearance. The chemical haze scatters blue light, which makes the mountains appear blue from a distance. It also gives the Smoky Mountains their smoky appearance. 

Great Smoky Mountains (NPS)

We learn such shocking things about nature. I had no idea before today that plants are polluting the air with volatile organic compounds, which when man-made seem to be about the worst thing under the sun. Yet here they are, also giving some of our national parks their distinguishing features and even namesakes. 

Information comes from National Center for Biotechnology Information and Department of Energy Office of Science.

Solar Energy

Solar power is another “clean” and renewable source that is emission-free and will never exhaust the sun. Not only do photovoltaic panels not drain the sun of energy, they do not diminish the capacity of other panels, so long as one panel is not placed on top of another.

There are two ways to use solar energy, active and passive use. Photovoltaic electricity (PV), solar heating and cooling, and concentrated solar are active systems. Passive solar building use design features capture and utilize solar radiation.

PV cells turn sunlight into electricity. This technology was accidentally discovered in 1954 when a scientist noticed that silicon created an electrical charge when exposed to sunlight. The solar powered calculator was born and eventually evolved into today’s solar panels. The early panels were made of silicon, but second generation panels use thin film and semiconductors. Thin film panels can be used as shingles, tiles, or façades and incorporate electrical generation into the design of a building. PV units can be found powering individual homes or on roadsides, collecting energy for lighting for highway signs.

How solar energy works (Sunpower)

Solar heating and cooling uses the sun’s radiant energy to heat or cool a building with the use of PV panels. A transpired collector is a black metal panel on the south-facing wall of a building that absorbs heat from sunlight. Holes in the panel allow heated air to pass through to the other side, where it is sucked into the ventilation system and throughout the building.

Solar process heating uses a solar collector (usually an evacuated tube or parabolic trough), a pump, a heat exchanger, and water tanks to heat a building. The evacuated tube is a series of glass tubes and reflectors that heat water inside. A parabolic trough is a U-shaped mirror focusing sunlight in a central tube. The focused sunlight heats water in the tube. The heated water is pumped throughout the building to warm it up. Solar cooling uses the same collection system, along with the magic of chemistry to cool the air.

Concentrated solar power is a generating system that reflects and focuses sunlight to create heat and steam that turns a turbine to create electricity. Because the system converts sunlight into thermal energy, it can be stored and generate electricity even on cloudy days or at night. Concentrated solar power can accompany a traditional fossil fuel plant as a carbon offset or as a stand-alone plant.

Solar array collection system (Colorado Springs Business Journal)

Passive solar uses site, climate, and material to use the sun’s radiant energy to heat and cool a building without the use of active mechanical systems like those mentioned above. Energy efficiency measures to reduce the required amount of heating and cooling is the first step. The second step is an unobstructed south face to maximize sun exposure. Sunlight entering the south facing windows is absorbed by thermal mass- material such as concrete, stone, or brick. The thermal mass absorbs heat from the sunlight during the winter and from warm air during the summer. Conduction, convection, and radiance are natural phenomena that circulate the heat throughout the building.

Like all other energy sources examined so far, solar energy is not completely “green”; it too has negative environmental impacts. Habitat loss for large solar arrays and concentrated solar plants can be mitigated by siting these in repurposed areas such as brownfields and reclaimed mine sites. Small scale units that power a single building typically have minimal impact, especially when roof-mounted.

Water use is a concern with concentrated solar plants. The sunniest areas in the US are often the driest, and water is scarce so a massive withdrawal of 600 to 650 gallons per megawatt hour of electricity can have a negative impact on desert denizens.

An additional concern is the hazardous materials used in the manufacture of PV cells. Many are used to polish the semiconductor surface and include hydrochloric acid and acetone. Petroleum is used in the manufacture of PV cells also, so even solar energy is somewhat dependent on fossil fuels. However, new technology that uses cotton and castor beans is being developed.

Next week we'll look at geothermal energy. This week's information comes from Solar Energy Industries Association, National Renewable Energy Laboratory, Renewable Energy World, US Department of Energy, Union of Concerned Scientists, and Scientific American.

Tidal Energy

Continuing the series on alternative energy sources, this week features tidal energy. It is similar to
hydroelectric power: it uses the same principles of water in motion and is also a “clean” energy source.
However, tidal power relies not on the temperamental flow of a river which is subject to effects of
weather and climate but on the timeless and ceaseless pull of the sun and moon on the world’s oceans.
Because of its reliance on ocean tides, this is considered a renewable energy source because it does
not diminish the amount of tides in the ocean.

Tidal power is also similar to wind power. Tidal turbines look like miniature underwater windmills.
Tidal turbines can be smaller and more densely spaced than windmills because water is denser than air;
less surface area is required to generate a comparable amount of electricity. While the wind may not
always blow, the tides are always in motion. 

Tide turbines (Forbes)

Another device to harness the energy of the tides is called a barrage. It is similar to a small submerged
dam that blocks the incoming and outgoing tides at the mouth of an estuary. A sluice in the dam opens
to collect the tidewater, which flows though and turns turbines to generate electricity.

One drawback of tidal energy is the tides themselves. Generation capacity is limited by the tidal cycle,
meaning peak demand will frequently be missed. Also, the change in tides must be at least seven
meters for this to be economically efficient. 

Barrages are limited by location. Not all estuaries are suitable sites. The equipment used for generation (either barrages or tide turbines) must be highly durable due to the unforgiving nature of the undersea environment.

Tidal barrage (Britannica)

Like the other energy sources previously mentioned, tidal power has negative impacts on the environment. However, due to limit use of this technology, these impacts are still being studied and at present are not certain to be occurring. The possible impacts include altered waves, currents, substrate, and sediment movement; loss of habitat for benthic organisms; noise that may interfere with biosonar; generation of magnetic fields; introduction of toxins in paint, lubricants, and antifouling; hindrance of fish passage; and fish being struck by blades or sucked into turbines.

This week's information comes from Marine Current Turbines, Ocean Energy Council, and Pacific Marine Energy Center. After a brief break for a look at June's Species of the Month, this series will resume with wind energy.

Betelgeuse Betelgeuse Betelgeuse!

You may have heard that Betelgeuse, one of the brightest stars in the night sky, is fading. The orange star forms the top left corner of Orion, probably winter's most easily recognizable constellations. Prior to this dramatic dimming, Betelgeuse was in the top ten brightest stars. Now it doesn't even crack the top 25. It's been clear the last few nights, and it seems to me that Betelgeuse is a little brighter than it had been, but it may be a matter of lighting since I live in civilization.
While the star will certainly end its stellar life with a supernova explosion, astronomers are fairly certain that won't be happening any time soon. Betelgeuse is a variable star, meaning its brightness changes, but that change isn't usually this noticeable or long-lasting. Current trending possibilities for the dimming are an ejection of dust or a cool surface area.

Betelgeuse's location in Orion (Constellation Guide)

If a cloud of dust came between Betelgeuse and Earth, that would obscure light from the star and make it appear dimmer. It could be an interstellar cloud or material ejected from Betelgeuse itself. The cool area on Betelgeuse's surface wold have to be very large to cause a noticeable dimming here on Earth. That cool spot would be similar to the sunspots we get on our own star, only much larger.
If Betelgeuse were to go supernova, it would be the event of a lifetime. In brightness, it would nearly match a full moon for months. It would be visible during the day for about a year.
This week's information comes from AccuWeather.

Oh Deer!

In August 2017 I had the opportunity to visit Springbrook Nature Center in Fridley, Minnesota. Located just outside Minneapolis, it's an urban oasis of forest, prairie, and wetlands. While walking on a trail through the wooded section, my companions and I saw a doe with two fawns up ahead of us. They crossed the trail and disappeared into the woods. I thought we were done with them. A few minutes later, the doe ran back across the trail the way she originally came from but without the fawns. My friend expected the fawns to follow any second, but they never did. What just happened?
The doe treated us as predators and was protecting the fawns. In her secret deer language, she instructed them to lay low on the forest floor. With their brown coloring and white spots, they would blend in well, even though there wasn't much sunlight dappling the ground that day. They likely had no scent, also. Meanwhile, Mama Deer took off running right in front of us, making as loud as crashing sound as she could. She wanted to attract our attention and trigger the chase response, leading us away from the fawns. Lucky for them, we're just normal humans who were out enjoying nature that day, not expecting to become part of it.

The doe came into view first

Later, we caught a glimpse of the fawns. One is to the left, the
other is slightly visible behind the doe.

This was the last wild adventure from my journey across the country that began with the total solar eclipse. I've shared some other stories from that trip, such as Volcanic Idaho, and there will be more to come in the future. If you plan on visiting the Twin Cities, here is a link to Springbrook Nature Center.

Transit of Mercury

Frequently, we observe solar and lunar eclipses here on our blue marble we call Earth. Solar eclipses are when the moon passes in front of the sun. Lunar eclipses are when Earth cuts between the sun and moon, with the moon covered in our shadow. Less commonly observed are planetary transits. Because we live on the third rock from the sun, we only get to see Mercury and Venus pass in front of it. Because orbits wobble and planes aren't aligned, this is something that is only seen a few times per century.

Transit of Mercury as seen with the unaided eye

Mercury transited the sun on November 11. Because the sun is so bright and Mercury is so small, a telescope with solar filter is a requirement to witness the event. I took a field trip to Philadelphia's Franklin Institute to see it for myself with their telescope. Because seeing Mercury normally requires a clear horizon at sunrise or sunset, most folks don't get to see it. This was my first time, and now I've finally seen all six naked eye planets- I included Earth, which I see every day.

Franklin Institute's telescope with solar filter

I got a shot of Mercury being live-streamed on the big screen

Sadly, I wasn't able to get my own pictures of Mercury, but I did get pictures. NASA was live-streaming and has a video up on their Youtube page. If you want to see a Mercury transit live and in person, you'll have to wait until 2032. You'll need to be in Africa, eastern Europe, or western Russia to see it. Otherwise, the next transit here in the states won't be until 2049. But if you think that's bad, the next transit of Venus won't happen until 2117.

NASA posted this picture of a prior transit on their Facebook page.
The little black spot on the bottom is Mercury. The one on
the top is a sunspot.

A Star Is Born

Stars are the most common object in the night sky. They come in different colors and brightness. Grab a pair of binoculars and the number you can see goes from too many to count to more than you thought possible. It seems as though they've always been there, but where did they come from?

Orion Nebula, a stellar nursery (NASA)

Gas and dust in space pulled together by gravity attract more material. More mass has more gravity, so it continues to attract more material, while also collapsing into itself. As it collapses and becomes more dense, it begins to hear up. At some point, what is now considered a core begins to fuse hydrogen atoms into helium. The pressure of the energy radiating from the new star is enough to keep it from collapsing into itself further.
Not all of the gas and dust gets sucked into the star. It will swirl around the star and conceal into planets and asteroids, like what happened here in our solar system. In other systems, multiple stars may form rather than just one like we got stuck with.

Life cycle of a star (NASA)

If a star is massive enough, it will blow itself apart in a supernova. Gas and dust from the exploding star will fly out into space and the process will begin again. This week's information comes from NASA.

Nature Minute Book Club

It's February and the days are getting noticeably longer, but we still have quite a few cold weeks ahead of us here in the Northeast. This month is like life in the Stone Ages: nasty, brutish, and short. I have snow coming twice before the Super Bowl is over, and I'm pretty sure more will be along shortly afterwards. Once the big game is over, what else is there to until spring but read? Having said that, feel free to peruse these titles from the Nature Minute book shelf.

Voyage of the Turtle: In Pursuit of Earth’s Last Dinosaur by Carl Safina

Safina travels the globe following sea turtles from their nesting grounds to their feeding grounds and points in between, looking for answers. What’s being done to protect them? What are the negative impacts people have on them, and how can we reduce or turtle-stomping footprint? Just where to they go and what do they do? If nothing else, you’ll learn just how immense these magnificent critters are and how they have adapted to a carefree life adrift and the challenges they face.

The Hidden Life of Trees by Peter Wohlleben 

Wohlleben, a German forester, takes us into the heart of his forest to show us how trees interact with friends and family, other tree species, and the animal world. Fascinating ideas about tree cognition, memory, and communication, as well as trees’ nurturing abilities will change the way you look at plants. Is a forest bigger than the sum of its parts? 

The Sun’s Heartbeat by Bob Berman

This book is the sun’s biography, from its humble birth to its spectacular future death. In between, learn about our changing relationship with the sun over the centuries, how it influences everything, and take a historical trip through own growing sea of knowledge about our nearest star. A seasoned skywatcher, Berman has yet to lose his sense of awe over solar eclipses.

Travels in Alaska by John Muir

America’s leading conservationist of the 19^th century recalls his journeys to Alaska in 1879, 1880, and 1890 in this book, which was still unfinished as the time of his death. Relying on his careful expedition notes, Muir gives a poetic narrative of his voyages exploring mountains and glaciers and documenting the flora and fauna of the Last Frontier while describing the scenery with a sense of reverence and awe. His love of life and the outdoors really shines through.

The Thing With Feathers by Noah Strycker

This book is about birds and people. Not relationships between the two, but common traits that will shock you. In some regards, birds are just as intelligent as humans. Sometimes, understanding their behavior helps us understand human nature. Deep down inside, on some basic level, maybe we’re not above the animals. Language and culture are thought to be defining human traits, but what happens when a “lower” animal develops art?

Lunar Lunacy

Next Wednesday (January 31) the world will be treated to a trio of rare lunar occurrences, all at the same time. A blue moon, super moon, and total lunar eclipse all fall on the same date. What are all of these? Let’s break it down one item at a time.

Humans love to name things, and a blue moon is simply when a second full moon happens in a single calendar month. Our first full moon was on New Year’s Day, which in itself is one of those rare events that people seem to think means something. Sometimes the moon actually does appear to be blue, but that is usually due to atmospheric issues like pollution.

A super moon is when the moon reaches its closest approach to Earth (the moon’s perigee). Our orbit around the sun isn’t round, it’s slightly elongated. The moon’s orbit of us is the same. When the moon is near or at perigee, it appears slightly larger than usual. It’s barely even noticeable to the human eye.

Diagram showing the moon's elliptical orbit (NASA image)

A lunar eclipse is when the moon passes through Earth’s shadow. This event only happens during a full moon, when the sun fully lights the side of the moon facing Earth. This puts Earth between the sun and moon. A solar eclipse requires a new moon, and places the moon between sun and Earth. During a lunar eclipse, the moon sometimes appears red. It’s also known as a blood moon. Next week we are treated to the rare super blue blood moon. That’s a mouthful!

Diagram showing the sun, earth, and moon positions during
an eclipse (Smithsonian Air and Space Museum)

NASA photo of a blood moon

The best lunar eclipse I’ve ever seen was in 2015. The eclipse began before moonrise, so by the time it came up over Mount Rainier it was already red. This time, I'll get to see it on my way to work, assuming we have clear skies.

Lunar eclipse over Mount Rainier

Partial phase of a lunar eclipse

Species of the Month

December’s Species of the Month, like last December’s, is a living symbol of Christmas. Holly, with its green leaves and red berries, has become of a jolly symbol of the most wonderful time of the year. The Species of the Month is American holly, native to the eastern US and lower Midwest.

Scientific name: Ilex opaca

Kingdom: Plantae (plants)

Class:   Magnoliopsida (dicots)

Order: Celastrales (flowering trees)

Range: New York and southern New England south to the Gulf Coast, west to Texas

Habitat: Well-drained forests, coastal areas

Lifespan: About 100 years

Diet: Sunlight and water

Predators: Insects including southern red mite, holly leafminer, and holly midge; fungal diseases; birds may eat the berries and herbivores may browse the leaves.

Conservation Status: No federal protection; listed as Exploitably Vulnerable in New York and Threatened in Pennsylvania.

Winter holly at Gateway National Recreation Area (NPS Facebook photo)

Other Information: American holly is used as an ornamental planting. Its branches are used in Christmas wreaths. The Pilgrims named American holly, based on its similar looks to their familiar English holly, which had been established as a Christmas decoration for some time. A slow grower, it is typically an understory plant, although some have been known to reach 100 feet tall. Because it is usually found in the understory, it is rarely the dominant plant in a forest. However, an excellent example of a holly forest can be found at Sandy Hook, New Jersey. Both male and female hollies flower, but only the females produce berries. Birds are an important method of seed dispersal. Holly’s wood is among the whitest woods on the market. It is not very strong so its commercial use is limited. Small green flowers are hardly noticeable.

This week's holly information comes from the US Forest Service. 

My 2016 Christmas card, featuring holly in my yard

Coastal holly in North Carolina (NPS)

More holly in New Jersey (NPS Facebook photo)

The Cosmic Ballet Continues

This Monday the United States will witness the rare and majestic total solar eclipse. Not all areas will see a total eclipse, but all of North America will see at least some of the sun disappear. While not a rare event, it is unusual for a total solar eclipse to cover such a large populated area. It seems like usually they happen only over the remotest part of the Pacific Ocean or exclusively at the South Pole. This eclipse will the first total solar eclipse to hit the US since 1979. That might not be too terribly long ago, but think about this: in 1979 there were still people alive who could remember the last time the Chicago Cubs won the World Series (1908) or fought in the war against Spain in 1898.

What is a solar eclipse? When the moon passes between the sun and Earth and casts a shadow on us, that’s a solar eclipse. They can only happen during a new moon, which is when the sun’s rays hit fully on the “dark side” of the moon, so it’s the only time you’ll ever see a new moon. New moons happen every 29 days, just like a full moon, but we don’t have a solar eclipse every month because of how the sun, moon, and Earth dance with each other.

Geometry of a solar eclipse- not to scale (from Nustem)

You’ll notice the sun is a lot higher in the sky now than it was in January. Because Earth is tipped about 23̊ as were orbit the sun while spinning in our tipped circle (which also wobbles) the sun appears to ride a squashed and stretched figure 8 across the sky called the elliptical. The moon does the same, but their ellipticals don’t always match. When they do, you get an eclipse.

Distance is also important. Neither Earth’s orbit nor the moon’s is circular; both are slightly elongated (an ellipse, hence the term elliptical) so sometimes the moon close enough to block out the sun during an eclipse and sometimes it fits inside the sun like a ring. This is called an annular eclipse. Like during a total eclipse, only a narrow band will see the annular eclipse, while everyone else gets to see a partial eclipse or nothing at all.

Annular eclipse (from Universe Today)

Partial eclipse (from Huffington Post)

Always practice safe eclipse viewing! Follow these tips from NASA. Never look directly at the sun, even during an eclipse. The only exception is during totality, and that is ONLY if you have totality where you are at, and it only lasts about a minute and a half. Use eclipse glasses- if you put them on and try to see anything but the sun, you should only see blackness. Sunglasses will not do the job. Never look at the sun through binoculars or a telescope, unless you have a solar filter. If your solar filter screws on to the eyepiece, it is junk- throw it away! If you don’t have any safe viewing equipment, make a pinhole viewer by poking a hole through a piece of cardboard and let the sun shine through. During the partial phase, you will see a spot of sunlight missing a chunk in the middle of the cardboard’s shadow.

I will be in Salem, Oregon for the eclipse, immediately preceding a very special Nature Minute road trip. Sorry, no live-blogging. I can’t blog while driving, and besides, there’s no wifi in the wilderness. Check back in September or follow along on Facebook for pictures and tales from the road.

This week's credits: Nustem, Huffington Post, Universe Today, and NASA  

Summertime and the Living's Easy

Summer is officially here, at least astronomically. Today marks the summer solstice in the Northern Hemisphere, while our friends south of the Equator are settling in for a long, dark winter. What exactly is the solstice?

Summer solstice is the point at which the pole of the hemisphere in question most directly faces the sun. It’s the longest period of sunlight in a single day and the sun reaches its highest point in the sky. At the pole, it is 24 hours of daylight. The length of daylight decreases with distance from the pole, culminating in 24 hours of darkness at the opposite pole. 

Solstice occurs at 4:24 AM Universal Time (time in Greenwich, England on the Prime Meridian) on June 21st. Sunset at my location is 9:07 while solstice is at 9:24, which is on the 20^th here. I won’t even see the sun when I am facing it most directly.

Interestingly, we associate summer with long days, but by the time summer actually arrives the days start getting shorter. And even though solstice is when we receive the most sunlight, it takes about a month before peak temperatures arrive. This is because the oceans affect heat absorption and distribution. For the same reason, peak coldness is usually a month of more after winter solstice. Of course, there may be exceptions but that is generally the norm at my latitude.

On an unrelated topic, this week is National Pollinator Week. Bats, insects (notably the bee), and the wind are pollinators you encounter on a daily basis. Go outside and hug a pollinator! Just not a bee.

Solstice diagram: http://www.almanac.com/content/first-day-summer-summer-solstice

The Worlds Around Us

This week’s Nature Minute is out of this world! Nature isn’t just limited to Earth. Head outside after sunset and check out our neighbors in the solar system. Venus is the brightest object in the night sky and you can find it in the constellation Aquarius, in the southwestern sky. If you happen to have a telescope handy, look for distant Neptune just above and to the left of Venus. Higher above Venus and more the left but still close by is Mars, which appears to be a bright red non-twinkling star. Jupiter is the brightest object (other than the moon) after midnight. Again, if your telescope is handy and you are still awake, check out Jupiter. You may be able to see some of its moons. Jupiter, the largest planet, is almost like a mini solar system within our solar system. If you are an early riser, or maybe just can’t sleep, Saturn and Mercury rise just before the sun. Mercury is hard to see because it is close to the sun and therefore always low on the horizon. In my area, trees to the west or Cascade Mountains to the east make viewing Mercury impossible. Saturn is a treat to view through the telescope. Its rings are not visible to the naked eye, but they pop when viewed through the telescope. I’ve seen them a few times before and I never get over it. It’s very surreal. It looks fake.

Lunar eclipse

Venus (bottom) and Jupiter (top) in conjunction

To check out the planets and stars, get out of town. The darker the sky, the better. Up in the mountains, in the desert, or along the beach are great places for stargazing. The full moon is your worst enemy, unless you are checking out the moon. If you want to check out Saturn or Mercury, use caution not to get your telescope caught in the rising sun, unless you happen to have a solar filter. In that case, you really don’t need to be reading this blog. You probably know more about space than I do. This week’s planetary positions are courtesy of the good folks at EarthSky.org.

Solar-powered Cycles

You probably noticed by now that the days are getting shorter and the air is a little chillier. Fall has fallen! The sun gives life to everything on Earth through heat and energy for plant photosynthesis. It also triggers changes in life cycles, some of which are evident to almost everyone right now.

The most obvious cycle that is affected by the sun is the current situation with our tree leaves changing colors and falling off. Because Earth’s axis is tilted 23 degrees, we experience seasonal variances in the amount of sunlight we get. As we move through fall and into winter, the sun sinks lower in the sky and light that hits us is less direct.

Nature loves efficiency, and trees lose their leaves this time of year because with decreasing sunlight, they would expend more energy performing photosynthesis (turning sunlight, water, and carbon dioxide into energy) than they would get from it. Chlorophyll, the active photosynthesizing pigment, dries up and the cells in the leaf stem die, weakening it to the point that it falls off the tree. Until spring arrives, trees and other plants live off of starches stored in their roots. That starch is the byproduct of photosynthesis.

Other seasonal cycles are the leafing out of trees, hibernation, and mating seasons. Some cycles run by the sun can be daily, not just seasonal. Dandelions and other flowers close their petals at night. Daily sleep cycles are also affected by sunlight. Animals don’t use an alarm clock, but they do have an internal clock.

Bigleaf maple

Even shrubs change colors