Author: tashastannett

Variability in the height of the Tropopause

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The tropopause is the boundary between the troposphere and the atmosphere.  It is literally defined as the point where temperature at altitude first stops decreasing and starts to increase.

The tropopause is not at a fixed height around the Earth.  It varies in height from approximately 9 km at the poles to over 20km at the equator.  The reason for the variation is that the tropopause is driven by a series of “cells”.  These are areas of circulating air.  There three main cells in each hemisphere of the Earth, they are (from equator to poles) the Hadley Cell, Ferrel Cell and the Polar Cell.

At the equator, the warm air drives powerful currents up to 20km.  In the northern hemisphere these currents then circulate northwards, lose their heat and descend at approximately 30o north.  This is the Hadley Cell.  This descending air drives another cell rotating in the opposite direction from approximately 30o  north to approximately 60o north.  This is called the Ferrel Cell.  The Ferrel Cell in turn drives the Polar Cell in the opposite direction again.  The Hadley Cell, Ferrel Cell and the Polar Cell act like a set of “cogs” driving against each other.  As we move northwards, the heat on the atmosphere reduces and the height of these cells reduces.  Hence the height of the tropopause also reduces.

Between the Ferrell Cell and Polar Cell, the polar jet stream flows from east to west at about 60o north.

The UK sits between approximately 50o and 60o north.  Close to the boundary between the Ferrel Cell and the Polar Cell and also often directly below the polar jet stream.  This helps to explain why our weather is often so changeable.

For our project, this explains why we have to be so careful on exactly when to launch our balloon.

We expect to encounter the tropopause at approximately 12km.  Our temperature is likely to be at least -40o C.  We are also measuring humidity on our payload and we expect that the humidity readings will also fall to very low levels at the tropopause.  This is because most of the water vapour in the atmosphere is below this level.

In the picture below, you can see the various cells in our atmosphere and the polar jet stream.  You can also see the variation in the height of the tropopause as you move from pole to equator.

references:

http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html

https://en.wikipedia.org/wiki/Tropopause

https://reader.elsevier.com/reader/sd/pii/S1878029612003349?token=4591DB2B7559029930EDCD4306AD3F5980AC6ACFB72C135656571ACC7889162524AD81A22D95FA0BCC6989E3212290D4

https://www.quora.com/Why-is-the-troposphere-thicker-over-the-Equator

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Earth’s Atmosphere – Painted Basketball Analogy.

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I want to explain and show you just how thin our atmosphere actually is.

The radius of Earth is 6400km, 99.9% of the material in our atmosphere is below 36km. This means that our atmosphere is a very thin layer in comparison to the size of the Earth. The Earth is roughly 177 times “thicker” than the atmosphere surrounding it. A good analogy to represent this can be shown by a basketball covered in a single layer of paint. The basketball symbolises the Earth and the layer of paint represents the atmosphere. From this analogy you can see how thin the atmosphere really is compared to the size of the Earth.

This is why early astronauts described our atmosphere as the “thin blue line”.

 

 

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Cosmic Rays

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We will be detecting radiation with our sensors primarily from cosmic rays. Jack has blogged about cosmic rays here

Here is some more in-depth information on the topic.

Cosmic rays may affect us more than we think.They are not harmful to us or any other life form, however they may be the cause of the necessary ‘mutations’ to our ancestor’s genes which has led to the formation of us. Ancient cosmic rays may have altered our DNA over thousands of years

Cosmic rays may also cause the ‘conductive track’ for lightning bolts to follow. It is nice to think of it like this: lightning is potentially following the track caused by an original particle which came from somewhere else in the universe.

It has been claimed that cosmic rays can affect the earth’s climate by increasing the cloud cover and creating the umbrella effect.(however there is research which suggests otherwise).

Cosmic rays illustrate two of Einstein’s theories.This includes : They create new particles from their energy (‘E=mc2′)and they ‘live’ for a much longer period of time and travel much further than they should (‘time dilation’).

 

references:

https://www.sciencedirect.com/science/article/abs/pii/S1364682611000691

https://www.technologyreview.com/2014/07/04/172152/comic-rays-neutrons-and-the-mutation-rate-in-evolution/

https://www.scientificamerican.com/article/experts-do-cosmic-rays-cause-lightning/

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Practical 5 Triangulation

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For this practical we simulated losing our balloon when it landed and pretended that when it landed the balloon had no GPS fix (therefore we would not have been able to track exactly where the balloon is from data it sent us and woudl have to rely only the fact that it was transmitting a signal)).

The way we found the balloon was to use the triangulation method. To simulate this we positioned someone with the transmitter in the middle of a field and took the bearings from the strongest signal. (the largest signal to noise ratio). We did this using the directional Yagi antenna and “sweeping” it back and forth. Once we took the bearing, we drew those bearings on the map next to a cross, which is where we were positioned. After taking our first bearing, we then went to different places in the field to complete the triangulation method. Once we had drawn the lines from each bearing. We drew a dot where our lines crossed and those dots together formed a triangle. This is where the ‘balloon’/ transmitter was positioned in the field.

Group Meet Up 2 : Mission Badge Competition- filming

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On Wednesday (24th June) when we all met up as a group at Beech Hill, we filmed a video to present to the students and staff of Eaglesfield Paddle Academy. The video explains what the project is and also about the mission badges.

For the mission badges the students will design a badge which can either be on the theme of science, John Dalton, Eaglesfield Paddle Academy or even a mixture of all three.

Here are some photos from our filming:

 

We all spoke about separate sections of the project.

 

 

 

 

 

how to tie off the balloon?

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In order to have a successful flight , when securing the balloon we need to make sure no helium escapes. We will do this by twisting the bottom of the balloon as soon as it has been filled with helium so none escapes. Then to secure it, we will get a couple of cable ties to secure the balloon before cutting the end of the cable tie and putting a small amount of electrical tape on the cable tie to protect against any sharp edges. We will then repeat this about 10cm further down the neck, then loop the neck (with loops to conect the balloon train) and then cable tie again.  See diagram below and the further picture in Jack’s blog.

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Why is the balloon called John Dalton?

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Dalton’s atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties. Dalton based his theory on the law of conservation of mass and the law of constant composition. The first part of his theory states that all matter is made of atoms, which are indivisible. Also, all atoms of an element were identical, different elements had atoms of differing size and mass.

We named our balloon ‘John Dalton’ because he was born in Eaglesfield which is a Cumbrian village close to where we live. All members of the Balloon X Cumbria project (Poppy, Jack, Joe, Natasha) went to Eaglesfield Paddle Academy [previously Primary School]. Dalton has a link to Eaglesfield Paddle as he taught at the predecessor of the school before going to Kendal where he continued his teaching.

Dalton has a link to the local church as well, because the church’s alternative name is the John Dalton Memorial Church, in recognition of the fact that this scientist was born in the village and was involved in early education here.

Therefore, to celebrate his connections, we decided to name the balloon after John Dalton.

 

 

Do we need to heat the payload internally ?

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When increasing altitude the temperature varies to incredibly low values. The troposphere ranges between 15°C to -60°C , in this layer of the atmosphere the temperature decreases.  As the pressure decreases so does the temperature because they are directly proportional therefore the rate of pressure decrease is the same as the temperature decrease. This is because there are less particles at lower pressures which is higher up in the atmosphere therefore there is fewer successful collisions between particles meaning less thermal energy is created. When we reach the stratosphere (aiming for 30,000m) the temperature starts increasing again from -60°C to around 5°C. The reason for the temperature increasing is because the ozone layer absorbs the ultraviolet light from solar radiation. The electrical components we will be using will struggle to work in temperatures such as these, however the balloon will only experience these temperatures for the duration of under 2 hours. Therefore we are including internal insulation which will maintain the temperature inside of the payload and it will not experience temperatures anywhere near -60°C . Also the payload will absorb some heat from the sun as well. Therefore we will most likely not need an internal heater because of the heat from the sun and the insulation will allow the technology to function.

references:

https://sciencing.com/earths-atmosphere-composition-temperature-19463.html

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