Saturday, 26 January 2008

Mississippi miscellany...

Yesterday, 25th January, I received a short text message from Mark with a few geographical and meteorological observations about Louisiana. It concluded "enjoying the flatlands but wish the wind and rain would leave me alone"... then on the Artemis diary "rain got very heavy in the afternoon - heaviest since Malaysia - and lightning storm at the end of the day".

The 25th January is coincidentally the day on which Robert Burns is remembered around the world and so in celebration of our national bard and because geography teachers are encouraged to seek cross curricular links here is how he might have described the day... !

The wind blew as 'twad blown its last
The rattlin showers rose on the blast
The lightning flashed from pole to pole
Near and more near the thunder rolled
(adapted very loosely from 'Tam o'Shanter')
On a more serious note, the weather has clearly been pretty awful in the last couple of days so the first bit of today's miscellany is meteorological. Mark should expect the weather to pick up considerably tomorrow...
The pressure map above for Sunday shows the front which brought the rain clearing east across Florida and high pressure building over Louisiana. High pressure normally brings clear skies and, with widely spaced isobars, light winds. The winds follow the isobars blowing clockwise around the centre of high pressure. At night time it will be cold because the clear skies allow any warmth built up during the day to escape to the atmosphere but during the day in these sub tropical latitudes, temperatures should rise nicely. That, at least is the theory! However, it would seem that the predictions for tomorrow are pretty much in line with that..

...very little cloud

....very chilly first thing in the morning

.....quite cosy by the afternoon

and light winds from the north.

Fingers crossed for a better day!

Yesterday, after bike repairs in Baton Rouge, Mark took a route through the area called North Shore. The shore in question is the north side of Lake Pontchartrain which lies between New Orleans on the delta of the Mississippi and the 'mainland'.

Lake Ponchartrain is, in fact, an almost enclosed shallow estuary of several small rivers flowing south to the Gulf of Mexico east of the Mississippi delta. As the entrance to the sea is very narrow and constantly silting, seawater does not penetrate far into the lake and so it is 'brackish' rather than salty. The role of lake Pontchartrain in the coastal defences of the area is well explained in the link above and, in particular, the events of Hurricane Katrina which made landfall here, are explained.

One of the things which you notice immediately on both the zoomed out and the zoomed in view of the lake is the causeway which crosses it. Despite being the longest bridge in the world, I was until today, completely unaware of its existence! The Lake Ponchartrain Causeway is actually two parallel bridges, each almost 24 miles long, the first built in 1956 and the second in 1969. They brought the North Shore into the New Orleans Metropolitan Area and made commuting a resonable proposition for the communities on the North Shore area. Because they miraculously survived Hurricane Katrina, they were a very important lifeline to the people of New Orleans in the aftermath of the hurricane. The view below looks north across the causeway towards North Shore.

I wouldn't like to leave this area without a little mention for the Mississippi delta! From the air it is one of those areas on our planet which I think are really beautiful...The sediment being disgorged by the river not only builds up new land but also gives a palette of shades to the waters of the Gulf of Mexico. The image above contains the main channel used by river traffic on the Mississippi but this 'finger' is just one of countless branches which make up the delta. Deltas form where a river loses energy when it enters the sea and deposits the load it is carrying. They can be arcuate like the Nile delta or 'bird's foot' as here on the Mississippi.

...but to get back to North Shore where Mark covered most of yesterday's miles. Both of the major settlements there - Covington and Slidell, where he overnighted, have seen massive population booms in the last two and half years as a result of resettlement by people who have chosen to move out of New Orleans. And here is some of the evdence in Covington.....I guess when you are clearing trees and laying out new building plots in a hurry, you don't have time to think up street names. It would be nice to think that the new residents now have more interesting adresses than A - K street or 1st to 3rd street!

The huge building boom in both Slidell and Covington is despite the fact that the lakeside area of Slidell lay right in the path of the eye of Katrina and suffered appalling flooding and storm damage as witnessed by these Flickr images.

1 comment:

meg said...

Fascinating info Mrs V . I too have never heard of the causeway - quite a photo of it too. Like the Mississippi Delta photo too. Now I am off to find some of those ox bow lake photos for my Geography classes.