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able and arrives at the same time every year meaning many of these regions have agriculture which relies on the arrival of the monsoon each year at a certain time for the crops and any delay or shift in timing can have a large impact on the crops and the food supply the monsoon we are most familiar with is the indian monsoon so i will briefly explain the mechanism behind this in india in the summer the air is very warm the further you go into the continent the warmer the air becomes and at the northwest end of the sub continent is a desert the thar desert which has extremely warm air during the summer months this warm air rises and because the air which has risen needs to be replaced cooler air moves in and this air moves from the ocean northwards over the continent this air contains a lot of moisture from evaporation over the ocean so now we have this very wet air moving in to replace warm air which has risen which would result in normal summer rains if it was not for the rather large blockade at the northern end of india which we know as the himalayas the warm moisture filled air cannot move further north into asia due to the mountains and it is forced to rise as it rises it cools and cool air cannot hold as much water as warm air so like the bottom of a water balloon bursting the moisture is deposited out of the atmosphere back to the ground whilst this is vital for agriculture and the plants on the subcontinent there is also a lot of damage caused every year by flooding and landslides with houses and roads washed away chittagong in bangladesh is a city within the tropical monsoon zone and these next images show the average temperature and the rainfall for each month note the low variation in maximum temperature and the very obvious spike in rainfall during the monsoon season average temperature chittagong image from weather and climate com rainfall in chittagong bangladesh image from weather and climate com the cool thing for me about the indian monsoon is that it only exists because of the himalaya mountain range blocking the passage of the air further into asia why do i think this is super cool because the himalayas are a relatively new mountain range geologically speaking and are only there because india went zooming across the ocean faster than continents usually move one theory suggests this is due to the plate being thinner than most other continental plates and so lighter and able to move faster it may also have got a slight speed boost by passing over a hotspot in the earths mantle and smacked into eurasia around 50 million years ago to put this in a time perspective this was after the era of the dinosaurs the himalayas are currently growing at around a centimeter every year due to the indian plate moving north east faster than the eurasian plate is moving north finally onto the savannah zones aw these regions have very obvious wet and dry seasons while these areas can have a lot of rain during their wet months it is not enough rain to qualify them as monsoons this change in weather is due to the movement of the ictz and the rainbelts which lie around it this image illustrates the dry season in brasilia which is as marked a difference as the monsoon in india rainfall in brasilia image from weather and climate com eeep this post got a little longer than i expected so next time we will briefly i promise cover the b and c zones posted in climate environment tagged climate environment itcz koppen climate classification monsoon tropical climate 2 replies tiptoes back in posted on october 4 2013 by skepticalsquirrel 5 so it has been a while you know how it goes you get caught up in something in my case my final semester of my bachelor and next thing you know it is 8 months later and then you feel awkward about returning after such a long break anyway i was asked if i would write up some posts on the ipcc report so i thought it was as good a reason as any to get back into blogging i thought i should start out with an introduction to climate as for me the systems themselves are fascinating and for a lot of people climate is some abstract concept only heard in relation to carbon dioxide and climate change when in reality it is so much more i hope i can show you at least a little window into our awesome planet in this post climate is defined as the pattern of variation in temperature wind humidity atmospheric pressure and other variables over a long period in a given region this is different from weather which is the temperature wind humidity atmospheric pressure etc at a given time in a specific location so climate is it is cold in sweden weather is it snowed today in stockholm the main factor affecting climate on earth is the incoming solar radiation which is unequally distributed across the surface of the earth being more concentrated at the equator and more diffuse at the poles this means the atmosphere is heated more at the equator and less at the poles as hot air rises and cold air sinks this unequal heating causes movement of air the air heated at the equator rises and moves towards the poles whilst the cooler air moves towards the equator to replace the rising air this results in loops of air circulation which are known as hadley cells in the tropical regions near the equator ferrel cells in the mid latitudes and polar cells at the poles global atmospheric circulation cells image from wikipedia in the areas where the air in the hadley cells is descending we find desert regions this is due to the air being cooler and containing less water than the warm rising air at the equator these cells of circulating air play an important role in many of the large scale phenomena such as the monsoon circulation in asia formation of hurricanes and the jet streams and trade winds which are caused by a combination of the circulating air cells and the rotation of the earth the rotation of the earth means that air currents do not move in a straight line but appear to rotate to the left or right depending on the hemisphere these two videos demonstrate the effect this first one is a simple experiment showing the phenomena this second video shows this effect in action and is an animation of annual air circulation i actually had an image of this as my desktop background for quite some time as i really love the visualization you can see the deflection of the air currents and the band across the equatorial areas known as the intertropical convergence zone itcz which is where the northern and southern hemisphere air meets next post in this series will cover the major climate zones on the planet and some of the driving forces and phenomena in each of them posted in climate environment tagged atmospheric circulation climate coriolis effect environment geography hadley cell itcz 5 replies shells who needs shells posted on january 23 2013 by skepticalsquirrel 9 exams all done now so back to the fun of blogging about awesome animals so far the molluscs we have looked at have had some sort of shell but not all molluscs have taken the shelled path today and in the next post we are going to meet some which prefer to be without shells and are in my opinion some of the most beautiful molluscs around so without further ado let me introduce you to todays topic the nudibranch from the latin nudus meaning naked and the greek brankhia meaning gills so literally naked gills berghia coerulescens a species of nudibranch image from wikipedia this group of animals has a whole lot of awesomeness going on some of which we will cover today and then it will spill over into the next post too for today lets take a look at the one in the video it is called glaucus atlanticus m and the reason it is awesome for me is that despite being a squishy little sea slug like thing around 3cm long it eats these physalia physalis better known as the portuguese man o war image from wikipedia now if there is one thing we know about portuguese man o war it is that it has a very nasty sting due to the trailing tentacles being full of cells which can fire toxic darts into its prey or into an unsuspecting persons leg see link here for post about man o war so how does glaucus cope with these stings there is a hypothesis that it releases mucus while eating the tentacles yes because it is small and the pmow is much larger it nibbles its way up the tentacles which protects its insides from the stings which can remain active for a period of time after the man o war is dead to make it even cooler it takes some of these stings and uses them in its own defense it goes a little something like this glaucus eats the tentacle with the stinging nematocysts within it some of these pass through digestion and end up in growths on the outside of the animal called cerata these then become part of the animals defense systems meaning it can fire them at any attackers it has primitive teeth denticles which it uses to chomp through its prey but also to hang onto them so this is a fairly cool animal so far but it gets even more amazing when you find out some other details about it this lovely little animal floats upside down so its top side is in the water and its underside is at the surface it floats because it has a bubble of air in its stomach but this means it has no way of steering so it floats around as the winds or currents take it in common with many fish which are found near the surface sharks for example it uses a form of camouflage which is known as countershading its top which is in the water is light silvery grey so it is difficult to spot from below whilst its bottom is a deeper blue or blue and white which helps it blend in with the water when seen from above i will leave this last image of glaucus atlanticus for you and next post we will look at some of the other animals in this family glaucus atlanticus image from eol encylopedia of life posted in biology evolution life on earth science tagged biology cnidaria education evolution life on earth nudibranch science zoology 9 replies sunday documentary posted on january 13 2013 by skepticalsquirrel reply yes yes i know it is usually the friday documentary but with everything getting back into a rhythm after new year i thought a nice sunday relaxing one would be ideal this is a bbc one from late last year about the life cycle of stars i started watching it last night aiming to fall asleep to it but had to stay awake to the end astronomy is not usually something i post about as it is not a subject i know much about but this one was fascinating enjoy posted in documentary interesting science science tagged astronomy bbc documentary education life life cycle of stars science stars leave a reply back with bivalves posted on january 8 2013 by skepticalsquirrel 2 so its the new year now i hope everyone had a nice new year with not too many hangovers last time way back in october i wrote about bivalves here and wanted to pick up where we left off so today is about their vision and movement as promised i am going to focus on scallops pectinidae as they have both interesting eyes and strange movement let s start out with the eyes you and me have two eyes and this is a fairly common number of eyes to have scallops however seem to be quite fond of eyes usually having between 40 and 70 but they can have up to 100 eyes on a giant scallop the dark blue dots along the rim of the shell image from wikipedia now not all eyes function the same way as ours do we have already met organisms with eyespots which are just a bunch of light sensitive cells able to distinguish between light and shade so the organism can move away from predators or towards the light for photosynthesis here the eyes of scallops are what is known as concave mirror eyes these are simple eyes which have a reflective layer at the back of the eye which bounces light back onto the cells which are able to process the light as they have so many eyes positioned along the edge of their shell they are able to follow an object as it moves past them rather than having to move their eye to keep it in focus they also have two retina in each eye one which responds to light and one which responds to darkness scallop eye showing the reflecting surface at the back which bounces light to the rods image from rewiring neuroscience com i have been trying to find other diagrams showing this and have come up with a couple of sites depending on how techy of an explanation you want opthobook com has a very simple diagram here and a little video explaining the basics of eye variation here for the more technical diagrams and explanations this paper by m f land 1965 is interesting here as well as this illustrative paper by colicchia et al 2009 here one final paper on comparative morphology similarities and differences between the parts in different organisms from speiser johnson 2008 here so apart from having more eyes than that teacher at school who always spotted you chatting not that i was ever talking during class of course what else is cool about these bivalves well i think sometimes a video says way more than i can by rambling so lets take a look at how these scallops move this movement is done by using muscles at the back of the shell to open and close it this pushes water out of the shell and the scallop shoots off like one of those bottle rockets you make as a kid with fizzy drinks they can control the direction of the jet of water so it is not a completely random motion posted in biology evolution life on earth tagged biology bivalve education evolution life on earth nature pectinidae zoology 2 replies antho what now posted on december 20 2012 by skepticalsquirrel 1 so after an extended break normal service is resuming although the post today will be slightly off the usual topic of the evolutionary journey as i mentioned yesterday i have been writing my bachelor project and i thought i would share with you a little of the topic i have written it on i could write a post which would keep my good e friend argyle sock very happy with lots of statistical stuff in it but honestly if i see the terms not normally distributed one more time my head may go pop also the actual topic is much cooler than the stats even though they are very cool too of course i would like to introduce to a group of pigments called anthocyanins these are the reason for the colour of blueberries blackberries some grape species olives and many other fruits and purple or red colourings in flowers like these pansies violet pansies the purple colour is caused by anthocyanins in the petals image from wikipedia the amazing bright red colours you see in autumn leaves is also down to anthocyanins so why have i spent this last semester writing about pretty red colours well here is where it gets a little more interesting not that pretty purple flowers are not interesting of course anthocyanins are also found in leaves which are not about to fall off the tree some plants have red leaves when they are young and some plants can turn on and off ...