Each year we experience two equinoxes and two solstices.  These four events are used to define our seasonal changes – officially that is.

Today is the autumnal or fall equinox in the northern hemisphere.  An equinox is simply the point at which the sun crosses the equator and day and night are of equal length.   In the northern hemisphere the fall equinox occurs in September (a slightly different day each year).  It’s the opposite in the southern hemisphere.

Today, September 23rd at 4:21 am the sun crossed the equator and the fall equinox began.  The fall equinox leads to the winter solstice when the night is the longest and day is the shortest (around Dec 22nd).  Again, the opposite in the southern hemisphere.   As the daylight hours reduce it gets colder, hence why the coming solstice officially kicks off the season of winter.

In Reality……..

The truth is the further north you live the earlier you start to experience the seasonal changes so although the equinox and solstice are good rules of thumb as to the seasonal changes and associated weather (brrrr!) they are not absolute.

Before I forget though, welcome to the first day of Fall 2015.  (Unless you live in the southern hemisphere than it’s the opposite.)

Of course if you live on or near the equator the seasonal changes are minimized.  It’s sort of like your weather is just one season year round.

Who figured this out and how did they do it?

Sometimes I wonder how human kind figured out the mechanics of the seasons, the cause (that is, earth orbiting the sun, earth rotating).   I only know this because I was taught in school and it makes sense,  so I believe it (and I guess Wikipedia say’s it’s true too so it must be).   It might be strange but I wonder if I was not taught about the earths obit and rotation would I have been able to figure it out.

It is actually pretty fabulous that others did all the analysis for us, does leave me wondering about my own capabilities though.

Again Happy Fall 2015 and don’t forget to bring in the tomatoes before they freeze on the vine – they won’t turn red and are not really edible after that.

Throughout the years the office buildings I have worked in generally practiced regular fire drills.  Sometimes you would get an advance notice (at least the managers would) and sometimes not.  The purpose was to make sure the occupants of the building could exit in an orderly manner following an alarm.

On the surface this seems like a good practice, however,  I would like to explore the value of this practice a little further.

Whats the impact and likelihood.

The risk event  (e.g., delayed exit during a fire, building collapse, attack by a jet airplane ) certainly has the potential for a high impact.    A delay or being trampled could result in death or serious injury.  For most of these risks though there are a number of mitigating factors that reduce the risk from occurring in the first place.  Things like regular inspections of buildings for fire hazards, early warning, special engineering for earthquake impact reduction and fire suppression devices are just among a few of these mitigating processes.   As a general rule, I would argue the likelihood of the risk event resulting in the need to exit rapidly is reduced to low by the various mitigating factors employed by building owners (recognizing some more than others, but building codes require a certain minimum level of mitigation.

So based on the assessment of high impact versus low likelihood how valuable is the pre-risk event mitigation of a fire drill.  One way to view this question is to consider the effectiveness of a fire drill.

My Experiences with fire in large buildings

I have only responded to three real fire alarms in my lifetime and all occurred in buildings where I had not participated in a fire drill  (two were hotels and one was an apartment building I lived in).  In all cases the building occupants exited rapidly, orderly and without incident.  Also, I can say with confidence the majority  (like me) had never participated in a fire drill in those buildings.

Unnecessary Risk Mitigation

Considering the effort, loss of productive work time and minimal risk mitigation value I am not a fan of fire drills.  Even without a practice drill the likelihood of someone not being able to exit or a mad panic occurring which delays the ability to exit is low in my mind.  And the impact would probably be quickly resolved.

And my final point would be the places where rapid exits from a building has resulted in people being trampled or injured usually occur at events (concerts, dances, etc) and generally none of these places (where the risk event has actually occurred in the past) conduct drills.  This of course is mainly because it is not practical.