Category: everyday science

Posted on by — 2 Comments

Everyday Science: Dormant Plants

We just moved to a new climate 2 years ago, and last year we planted our first plants in the garden.

There’s 5 of them.  I have a brown thumb.  I wanted to hedge my bets.

I spent the summer watching my new plants nervously.  Watching them, watering them, and waiting for them to die.

This might seem morbid, but you have to understand my history with gardens.  In the past homes we have lived in, and past climates, I successfully managed to find the plants that would grow best by reading gardening books, asking at Lowe’s, stalking my neighbors’ gardens, and trial and error.  I wound up with the most hardy native plants, ones that required little water above natural rainfall, and ones that would survive my gardening ineptness.

When we moved to Colorado, I got this book to prepare for another round of gardening failures, and found out…. I had been xeriscaping all my adult life!  Excellent.  I felt ready.

I planted my 5 Russian Sage plants and watched them flourish.  Feebly.  Then November came, and sure enough, they were dead.

Or were they?

I’m going to admit this because its in a blog, and you don’t know me or where I live.  Probably.  I actually snuck over to a neighboring subdivision and poked into their subdivision entrance display, which back in August I remembered had been chock full of healthy Russian Sage,….  and I broke a plant.  (Sorry, HOA people, but I’m sure your plant will be fine, just read this blog post!)   I snapped off a section to see if it snapped off just like mine did, and it did.  Excellent!  I think.

Again, you have to understand I have spent my adult life gardening in tropical climates.  We’re talking blue plumbago and hibiscus here, the ones that they grow in the greenhouse in Colorado, not outside…

I vaguely recalled something from biology class.  I’ll share.

Dormancy is a temporary state of slowed metabolism.  Plants go dormant in response to adverse growing conditions such as extreme heat or cold.  They go dormant in response to environmental conditions such as decreased amount of sunlight received in a day and colder temperatures.

What causes plants to react this way?

Plants have a hormone called abscisic acid (ABA) that contributes to the onset of dormancy.  When a plant is subjected to extreme conditions such as falling temperatures, ABA buildup allows the plant to deal with the stress by suspending growth of new foliage (in the vascular cambium, if you’re curious).

Abscisic acid levels in a plant are diminished by increased exposure to sunlight, warmer temperatures, and by heavy rains.  These conditions usually occur in the spring, of course.  Realize too that some winter-blooming plants are dormant in the summer months.  In their case, it would be cool fall rains that would trigger these plants to emerge from dormancy in the winter.

Plants have an internal clock that helps them remain in dormancy until it is time to grow again.  A certain number of cold days is required to break down the ABA within the plant and stimulate growth once more.  If there were an unseasonably warm day mid-winter, the plant would remain in dormancy, since its measure of cold days were not yet complete for the season.

When you force a bulb indoors, typically a late winter to early spring activity, you are actually triggering the plant to emerge from dormancy by introducing light and warmer temperatures.  (I have never actually attempted this myself.)

The levels of ABA differ from plant to plant, which is why some plants tolerate stressors such as cold winters more readily than others.  I’m guessing my Cape Blue Plumbago had much less ABA than does my Perovskia atriplicifolia.

For now, I think my Russian sage will successfully emerge from dormancy this spring ready for new growth.  But I’ll know for sure when it happens.

Helpful suggestions?  Comiseration?  Gardening pointers?  Leave a comment!



Resources:

Abscisic Acid.  Retrieved 10 Feb 11 from http://www.plant-hormones.info/abscisicacid.htm

What is Abscisic Acid?.  Retrieved 10 Feb 11 from http://www.essortment.com/abscisic-acid-61473.html

What Causes Plants to Become Dormant?.  Retrieved 10 Feb 11 from http://www.ehow.com/how-does_4914915_what-causes-plants-become-dormant.html

Nature’s Timekeeping.  Retrieved 10 Feb 11 from http://ceeldorado.ucdavis.edu/files/17562.htm

Posted on by

Everyday Science: Snowflakes

Snowflake photo through compound microscope by Wilson “Snowflake” Bentley, from snowflakebentley.com

Snow. It’s that time of year. Some of us have received a whole bunch so far this winter, and others… none at all. Still, everyone knows about snow. When it’s warm and the clouds come, it rains. If it gets cold enough… it snows.

Snow is the result of the saturated clouds of water vapor whose droplets of water attach themselves to ice particles. They attach and they freeze. Frozen ice particles grow when they encounter more water vapor. Sometimes they mix with other particulate such as dirt, smog, dust.

When the frozen ice particles grow so big that their weight is too heavy to be tossed about within the cloud, they fall out of it. Another way to say this is that the fall speed of the ice particle exceeds the upward air drafts within the cloud.

Note that for the snow to hit the ground as snow and not rain, the temperature all the way down must be below about 32° F. That snowflake has to stay below freezing or it will turn to rain. Even if it is above freezing where you sit, at ground level, if the majority of the air on the way up to the snow cloud was below freezing, chances are that snowflake will remain a snowflake long enough for it to hit the ground.

And the shape of a snowflake? It has six sides, a function of the molecular composition of the snowflake. Snow is water, and the H2O molecule consists of a central oxygen atom with two hydrogen atoms joined to it on either side at 104.5° angles. This V-shape with a negatively charged oxygen atom and positively charged hydrogen atoms means that additional water molecules that attach will do so in a particular shape. A 6-sided one.

It follows that larger snowflakes are formed in higher water-vapor conditions within the snow cloud. Smaller more compact snowflakes mean lower water vapor content aloft.

The actual shape of a snowflake can even be predicted by the temperature, as seen on this chart from Chemistry.com:

  • 32-25° F – Thin hexagonal plates
  • 25-21° F – Needles
  • 21-14° F – Hollow columns
  • 14-10° F – Sector plates (hexagons with indentations)
  • 10-3° F – Dendrites (lacy hexagonal shapes) 

As an activity, you can bundle up and head outside and see what shapes of snowflakes you can find.  Take this printable resource with you on snowflake types (or leave it inside and come back and refer to it over a hot cup of cocoa).  And for more fun activities and resources check snowcrystals.com.

    For fascinating reading about Wilson “Snowflake” Bentley and his snowflake photography, check out the website here.

    Posted on by — 1 Comment

    Cool Science Experiments- The Way to Get Your Kids Excited About Science

    By Marianne Vanderkolk at Homeschool-articles.com

    I love seeing kids excited about science.  Reading about science, exploring the world outside, seeing a science video are ways in which children enjoy and become motivated about science.  And, through the years, that is what we have successfully done. However, recently it has been confirmed in my own mind, that a real and extremely valid way for kids to love science and be keen to know more, is to provide them with time to play around with really cool science experiments.

    As a homeschooling family we have questioned, “What have been the things that we look back on with fond and treasured memories in science?”   It is either the hands-on nature walks and finding animals, or the fun in setting up and doing an experiment with great results.  Many of the experiments my children have enjoyed have been totally unrelated to any science text we may have been following at the time.  Most of the successful ‘science’ messes have sprung up from their own interest and trying to solve a question which they have posed themselves. (Like fixing a cheap toy and making it far better than it ever was.)

    So, how do we encourage our children to play around with science?

    Ask Them Questions
    Firstly, ask your children questions without giving away the answer.  If you are working through a text which has science experiments, present the question to them and don’t read or let them read what sorts of results they should be getting from performing the experiment.  Ask them questions during the experiment and after it – what do you think would happen if we changed  x, y or z?

    Ask them questions about life – about their physical environment or why things happen?  Ask them the curious questions before they ask you.  And then let them think and ponder about it.  It does not mean that you should never give answers, but at the same time, don’t rush in – give them time first.  When answering, relate the answer to their current experience.  And remember, it is okay to admit you don’t know the answer – that can become an ideal time to discuss how to research and find answers we are looking for.

    Let Them Experiment
    Let them play with all sorts of things around the home and experiment.  Using a book or science course will give you ideas about exciting science experiments. There are also a ton of books at the library that will interest your children.  Recently, I discovered an online science Curriculum which is full of really cool science experiments.  You can see some here.

    The experiment instructions are also on video, which we all really love watching. Using all sorts of common household materials, and some that you need to buy, these experiments have amazed and excited my children.  In fact, it has been the recent catalyst for a whole heap of hovercraft experiments which in turn has motivated my other children to fiddle with a toy gun changing it from a gun using air pressure to one using spring mechanics.

    Be Prepared, Grow a Collection of Science Tools  and Encourage Mess
    If you want your children to experiment, you will need to accept and even encourage mess.  Set up some boxes where you keep all sorts of odds and ends which will come in handy for science experiments.

    • You will need materials like rubber bands, straws, pipe cleaners, paper clips, balloons, popsicle sticks.
    • You will also need tools and materials to bind items together like sticky tape, masking tape, hot glue gun, super glue, rope or string, stapler and staples, hole punch, scissors.
    • Then you will also need to collect some clean junk – bottle tops, soda bottles, clean cans, bottle lids, ice cream containers and cardboard boxes of all sizes.

    Perhaps you can create a science corner – filled with experiment books and all the materials, and a table to work on.

    Allow for Mistakes
    Every science experiment does not need to work perfectly and make sure your children know that.  When an experiment does not work the way they had hoped,  ask them:

    • “What did you learn from that?”
    • “What might you do differently next time?”
    • “Why do you think that happened?”

    Be Curious Alongside of Them, But Don’t Take Over
    When your children are in the middle of a project or have completed it, they love to have a fan club.  As they become more independent, they may not need you to set up an experiment or help them do it, but they really want to share their enthusiasm with an interested party – like their family and parents! So, let them inspire you – cheer them on as they set up an experiment – ask them questions so they can verbalize what is happening and why – problem solve with them – search out answers together,  BUT don’t take over.

    As parents we have the tendency to ruin the child-led learning experience and make it a full-blown lesson.  We want to run with their idea because we can see how it will make a wonderful ‘unit study’ and so we plan, get books, blah,  blah, blah, and  run off with all of our great ideas, but meanwhile our children have turned the corner, lost interest  and moved on. It doesn’t matter!  Even if their interest in that topic may have been short lived, another experiment at a later date will most likely, help to reinforce the science concept.

    So, do what you need to do to excite your children about science.

    Be curious, ask questions, encourage messes, grow a collection of science tools and find materials to help you.  You can find some easy and totally ‘cool’ science experiments. as well as links to science experiments on video, plus two free Science Experiment Ebooks (A Science Experiment Guide usually valued at $25, and a Science Activity Manual and Video Guide valued at $30) , here – easy science experiments.