Friday, October 6, 2017

The Shopping Mall Effect

Economists use the term "shopping mall effect" to describe what happens when many shops are located in one place:  they draw more customers than the individual shops each would if they were scattered.  People are attracted by the opportunity to see many things at once.  People come to shop in one store and make purchases in others.  Every store benefits.

Ox-Eye Daisy
Flowering plants often use the same strategy.  Daisies and other members of the Aster family have “flowers” that are actually made up of many flowers together.  If you look closely at an ox-eye daisy you will see that the yellow center is actually around 100 tiny fertile florets.  The white “petals” are 20 white sterile florets that act as advertising for the food available at the center.

Calico Aster
Ox-eye daisies have only one flower per plant but many asters double up on the advertising by having dozens of compound flowers.  Pictured here is a calico aster.  At this time of year they are covered with bees that have been attracted by all that food in one place.

Calico asters go even further in attracting pollinators.  Instead of dropping flowers once they have been pollinated they keep them as part of the advertising scheme.  Huge masses of white and yellow – and red.  The pollinated flowers turn red in the center but are not dropped.  The result is a mass of white, red, and yellow like calico fabric.

I'm just wondering if anyone is reading this.  If you are, a comment would be appreciated.

Tuesday, October 3, 2017

Bee Frenzy

This is about plants and light.  Or plants and a lack of light.  And bees.

The days are rapidly getting shorter now as autumn winds down.  Bees are rushing about, taking advantage of the masses of blooming asters to finish up their food supplies for the long winter.  There is a huge border behind my house just filled with white asters and I can hear the bees buzzing from many feet away.

The question then is why the asters are blooming now and not earlier in the season.  The answer is something called photoperiodism – in other words, a reaction to the amount of light, and the chemicals that keep plants from blooming.

Except that when it comes to flowers, it is the lack of light that does it.  The chemicals that affect blooming are unstable in darkness and break down at night.  So asters and goldenrods and mums can’t bloom until the nights are long enough for much of the chemicals to degrade.  Then they can bloom.  They are what are called “short day plants”.  They only bloom when the nights are longer than 12 hours.  Other plants are "long day plants" that only bloom when the spring days grow long enough, and some plants just don't care.  The dandelions that brighten up our lawns will bloom all year long.

So consider this:  all of those artificial lights like streetlights and flood lights on your patio can be keeping your fall garden from blooming, and the same goes for plants inside.  That is why last year’s poinsettia isn’t turning red this year.  Keep it in a room without artificial lights and it will brighten up.

Does this artificial daylight affect birds and amphibians and insects also?  You bet it does.

Monday, October 2, 2017

Going Out On A Limb - Predicting The Weather

Last night I turned up the thermostat for the first time this fall.  In another week or so I will light the stove and it will burn until April.

The question now is, how cold will this winter be, and how much wood will I need? 

Predicting the weather over a long period has always been tricky, since there are so many variables that change from hour to hour.  Climate change makes it more difficult as the rules are now changing. 

I checked the reports from NASA and NOAA, the two government agencies that study the weather, to see what trends they are seeing.

One indicator is the ENSO, the El Niño-Southern Oscillation.  Normally the winds in the tropics blow from east to west – the easterly trade winds.  This pushes tropical warm ocean water away from the west coast of the US, allowing cooler water from the ocean bottom to well up along the coast.  The result is the cool, dry, weather and the great fishing of southern California.  (It also blows hurricanes from Africa to North America.)  

If during an El Niño the winds slow down, the warmer water sloshes back towards California.  This warmth and resulting low pressure will pull the jet stream southward, giving wetter weather in the south and drier weather in the north.

If the trade winds speed up and push the warm ocean water further from North America, a phenomenon called La Niña, the opposite occurs.  The jet stream will be pushed up by the high pressure over the colder water, bringing wetter, warmer weather up to the north.

Currently it appears that the El Niño winds are slowing down, but with a only small chance of a full La Niña (stronger trade winds) developing.  NOAA thinks that there is only a 62 percent chance of La Niña development during November-January 2017-18. The official outlook indicates a likely return to ENSO neutral conditions by next spring. Based on that, there are some long-range predictions that might be made.  

With a slowing of the El Niño winds, the average temperatures in the US could be slightly warmer than normal.  The precipitation (as of today) is expected to be normal.  Unfortunately that combination could mean more sleet and ice.  

Remember that ENSO is only a part of the prediction, but as of right now it looks like pretty much like slightly warmer and slightly wetter than normal this winter in New England.

Then there is the polar vortex.  There are several high-speed winds that circle the earth;  you have probably heard of the jet stream.  These upper atmosphere winds are caused by the difference in temperatures between the equator and the poles. 

Normally the polar vortex traps the coldest air at the north and south poles.  But (as formally denied by the best politicians that money can buy) as the earth’s atmosphere heats up, and the poles are warming at a faster rate than the equator, there is less and less difference in temperatures and the polar vortex weakens.  The cold arctic air is not being contained at the dark north pole as the vortex slows down.   It comes down to visit us. 

As of right now there are no specific warnings about the polar vortex for this winter, so my prediction remains at very slightly warmer and wetter than average for New England.