D-Day….Do it !
The Pain has gradually got worse over the last couple of weeks until it eventually made me sick. In truth I am not sure what actually made me sick. It could have been the excessive medication or the pain, either way it wasnt very nice. So ten days ago I booked a doctor’s appointment to see try get some pain management sorted out once and for all. Ten days to wait for an appointment, what is the world coming too. Ok, Easter had positioned itself right in the middle but what can you do about that. The whole system seems to grind to a halt for that reason yet aircraft still fly, Hospitals still care, Police still patrol and shops still open.
So I carry on, the pain is there but I still…carry..on…. I must, I have a wife and children and I have a purpose too. Otherwise we give up.
I am now going to grumble about the weather again. Yesterday I ventured out early in the frost to be greeted by a very clear but beautiful dawn. Tarnfield Park at sunrise is sublime. Less than half a dozen people are around at 6:00 am and it feels like you have the place to yourself. That is of course if you choose to ignore the abundance of bird life. Yesterdays sunrise was somewhat bland; a distinct lack of clouds to create some colour and the whole image lacked another dimension if you know what I am getting at. It looked more like a small silhouette with an enormous orange to blue graduated filter; something I could have created in two minutes using Photoshop.
Bad news….this morning was exactly the same. This got me thinking so I decided to look back through my archives and in particular last years images from this time. Guess what?
Cloud !! Well, just a little bit. Every image from around this time appears to have very little cloud. I have studied sunrises and sunsets for years and if you look through my pages on here you will see a full article on them. The temperature has a huge influence on clouds; during sunrise and sunseta good opportunity arises to observe different aspects of clouds. During these periods, changes in the contrast and colour are observed as well as structure of the clouds. Such sunrises and sunsets can develop into some of the most spectacular events that exist in meteorology.
Obviously, sunrise and sunset are mostly noted for the associated changes in the colour of the sky especially around the sun. On some occasions, clouds will also reveal different colour patterns if present around sunrise and sunset. It is very difficult to describe the various colour changes that occur with the different clouds around these times. But there are general stages that are associated with the times from dawn to sunrise and sunset to dusk.
The heights of the clouds have an important influence on the length of times that cloud reflections occur. The higher the cloud, the longer the cloud bases will be able to reflect light. In fact, high clouds will reflect light for periods of up to 30 minutes whilst low clouds will typically reflect light from their bases for around 5 to 10 minutes. The reason for such a vast difference is that lower level clouds near the horizon are much closer to the observer ( around 1 to 15 kilometres away) than clouds at higher levels which may be up to a few hundred kilometres away. The cloud bases of higher clouds therefore reflect light well before sunrise and remain so until just before sunrise. The same situation still applies for sunset but in the opposite order. The process of sunrise and sunset obviously occurs in a set pattern. Let us consider only one level of cloud in the sky. The cloud closest to the horizon will reflect light first. Gradually, clouds further away will also begin reflecting light. The process continues with colours changing from red and pink to yellow although occasionally some blue or violets are also observed. This of course depends on the heights of the cloud and the patterns of their bases.
Now, if combinations of clouds occur, then different patterns will be observed representing the different reflections of light from different levels of clouds in the atmosphere. This means that the higher clouds are still reflecting light from the sunrise for instance and lower level clouds are only observed as darker regions with no light being reflected from their bases. In the case of the lower clouds in particular, their shadows are observed as well as the sun’s rays. This provides the observer with the opportunity to observe the outline structure of the clouds, especially cumuliform clouds with rounded tops such as cumulus.
During sunrise and sunset, even the same types of cloud may appear different in various regions of the sky. Cumulus, for example, will reflect more light at the opposite regions of the sky to that of the sun as compared to cloud closest to the sun. This creates a varied contrast and must be taken into account by observers trying to determine the different types of clouds in the sky.
Sunrise and sunset represent a short period of time where there are changes in the intensity of light and the colour of the sky signifying the transition between day and night. It is important to note that sunrise and sunset occur as a result of the earth’s rotation and not the movement of the sun around the earth. We obviously know the sun does not revolve around the earth. Nevertheless, it is more “convenient” to associate the sun as the object moving across the sky (which is its relative observed motion) especially when referring to and explaining weather concepts.
Both sunrise and sunset reveal changes in the colour and intensity of the sky during the morning and evening respectively. The changes in colour occur due to light passing through the atmosphere being scattered at different frequencies. The frequencies that lie in the spectrum of red will be scattered by light particles more than those frequencies in the blue spectrum. This means that the sky near the sun on the horizon will appear red since the light will be scattered to the observer. On the other hand, red light from the sun whilst it is well above the horizon will be scattered away from the observer. The light from the blue spectrum will be scattered least and hence pass through the atmosphere straight to the observer. The sky therefore during the day will normally appear blue. The light during the period from dawn to sunrise increases in intensity near where the sun will eventually rise and eventually covers the whole sky area. The intensity also increases radially away from the sun’s rising position. It therefore becomes easier for an observer to predict where the sun will rise. The process during sunset occurs in reverse.
Of course there are other factors that influence how sunrises and sunsets vary from one location to another. The latitude is one of the most important factors and is directly associated with the length of sunrises and sunsets. For instance, in the most extreme case, both the north and south pole during their respective summers have 24 hour sunshine just above the horizon and therefore have the longest sunrises at certain times of the year. During winter, the sun is non existant with complete darkness.
Another factor is the altitude. In fact, altitude can influence the appearance of sunrises and sunsets in two ways. First, if the observer is located in high mountains, the sunrise and sunsets may appear earlier or later depending which way the mountain faces . Second, if other areas exist to disturb the pattern of the normal landscape, then this will influence the amount of colour visible during sunrises and sunsets.
I am yet to edit the images from yesterday so this morning’s is at the back of the queue. I will post the image as soon as I can. Breakfast next, then the doctors waiting room. Cross fingers.
Bye for now.