What you need to know about Tropical Cyclones.

 

For those who read the news and have seen Storm Alberto heading towards Lake Michigan (for the first time ever), you may still be wondering what a ‘Tropical Cyclone’ is and why they always seem to be in the same region. Here are some facts you might like to know as we enter the Atlantic storm season.

1. What are they?

A tropical cyclone is essentially a system of low pressure over tropical or sub-tropical waters. These systems contain thunderstorm activity (otherwise known as convection) with slow-moving winds that can circulate both clockwise and anticlockwise; anticlockwise in the northern hemisphere and clockwise in the southern hemisphere.

2. Why are they called different things in different places?

It confused me for a long time; is there a difference between Cyclones and Typhoons? If there is, what is it? Well, it turns out it’s just a geographical difference. Once wind in the system has exceeded 74mph, in the Atlantic it is classed as a Hurricane and the eastern Pacific whereas, in the western Pacific it is classed as a Typhoon. Areas such as the Indian Ocean and South Pacific, it can be classed as a Tropical Cyclone or Cyclone. The literal only reason for these different terms is dependent on where the storm forms.

Image result for map of tropical storm

3. Why do they have personalised names?

This is just so there is an ability to distinguish between the storms as there is likely to be more than one per year. Also, the names don’t keep going down the alphabet until ‘A’ is reached again. Every year the first storm will start back at ‘A’ and will then continue down the alphabet until the new year is reached. After 6 years, the names are recycled, so for example, if there was a Storm Alice in 2011, Storm Alice would then be used again in 2018.  This system started in 1953 by the National Weather Service whereby it was also stated that the letters Q, U, X, Y and Z shall not be used. The furthest it’s ever come to reaching the end of the alphabet was in 1995 when 19 named storms passed over the Atlantic ending with Storm Tanya which dissipated on the 1st November 1995. Also, extremely intense and destructive storms (that are potentially Category 5) are not used more than once to show sensitivity to people that were affected by these events. (The National Hurricane Centre has a list of retired names on their website.)

4. How do they form?

In the tropics, there is an area of low pressure which is above and below the equator. Above the equator the winds blow north-west and below, the winds blow south-east. When these two meet, they are moving in opposite directions so can spin around each other. Not only this, they require warm water to form which means that the warm air (usually around 27 degrees C) on top of this ocean rises, causing an area of low pressure. Underneath the warm air system, the cooler air is moister and forms clouds underneath the warm air. This whole system is fed by the warm ocean and the two sets of winds that cause the motion of the cell.

Image result for formation of cyclones

5. When might they occur?

As the previous point suggests, they are caused during warm seasons during peak level of solar radiation. The ocean itself reaches its maximum temperature a couple of weeks after this peak and thus the storms will start occurring usually during the late stages of summer and early autumn. This occurs from July to September in the Northern Hemisphere and from January to March in the Southern Hemisphere.

6. How do they die out?

In the most basic terms, when these systems reach land or cold water, they are no longer being fed by the warm ocean. This means that they are not being fed any water or convective energy to use so therefore they weaken. Another way they could weaken and die out is when dry, cool air is suddenly present in the system, this reduces the possibility of convection to keep the storm going.

7. How are they ranked?

There are multiple different scales used to measure their intensity. The most common scale uses wind speed to measure its intensity and is called the Saffir-Simpson scale.  Category 1 is the weakest form of a cyclone and Category 5 is the strongest.

Not only is wind speed used but also a less objective measure can be found. This might include observations of destruction the cyclone causes. For example, a Category 1 might only damage some crops and trees but no houses whereas a Category 5 would cause extreme and widespread destruction. There is also a scale for this subjective measure which is called the Beaufort Scale which is a scale from 0 to 12 (similar to that of the Modified Mercalli Scale for earthquakes). This scale covers all wind speeds and not just storm events. It starts at wind speeds less than 1km/h and escalates to hurricane force winds at over 118km/h.

Not only are there different types of scales, but the different geographical regions have all have their own scales with different categories for the severity of cyclones.

8. How are they forecasted?

Due to technological advances in meteorology in the past 50 years, computer modelling, stationary satellites, ships at sea and aircraft can all predict the formation and track of cyclones.

Organisations such as the National Hurricane Centre in Florida track specific areas of the ocean that are susceptible to storm events to measure changes in pressure and seeing clusters of thunderclouds that could lead to tropical depressions. Once a storm system has been detected, computer modelling, synoptic forecasting and statistics can predict what the storm is going to do from studying previous storms. (Of course, you can’t control mother nature so predictions may not be completely accurate).

9. Could they occur in the UK?

In theory, they can’t as they are tropical features that occur in latitudes up to 20 degrees away from the equator. However, the UK can receive areas of low pressure that have originated as tropical cyclones but have moved to higher latitudes so are technically cyclones/hurricanes. It is very unlikely that the UK will receive extreme cyclones found in Central America as the sea surface temperatures are not warm enough and the area of depression is not low enough. This did not stop Storm Rachel in February 2018, Hurricane Ophelia in 2017 and Storm Rina in 2017.

 

ophelia.jpg
Photo of the strength of Storm Brian in the UK in 2017

 

10. Are they affected by climate change?

This is a million dollar question (quite literally) and is not yet fully understood. It is theoretically thought that a rise in temperature by 2.5 degrees C could double the amount of storms we receive as warmer temperatures cause warmer oceans which cause more evaporation and could cause more storms. However, the Intergovernmental Panel on Climate Change (IPCC) thinks that the frequency of storms will stay the same (or even decrease) while their intensity goes up. It’s clear that it’s not yet fully understood and will need to be further researched in order to help to reduce the risks in association with them.

If you have any questions or points of interest, please feel free to comment below or send me a message on Instagram @_alicefowle_

Cover photo taken from here.

The Earth is flat. Arguments and Responses.

Do you believe?

It seems to be a hot topic at the moment. Is the world really flat? Are all photos from space a conspiracy from NASA? Well, I’ve decided to outline the arguments for and against this ‘flat earth’ theory because really, I do think it is pretty stupid. I know a lot of these arguments may make sense but listening to science, astronomy and physics, I think it’s difficult for these arguments to stand.  If you still believe in the Flat Earth theory after hearing these arguments then I have to shut up, but from an earth science perspective, I couldn’t understand why you would actually believe this (though that won’t stop me from wearing the t-shirts).

The earth is surrounded by an ice wall

As the animation shows, the earth is seen to be a disc that is surrounded by an ice wall that manages to hold oceans back. According to conspiracists, explorers have traveled here but have not returned to tell the story and now travel is banned to Antarctica for these reasons.

This doesn’t make sense. They believe that if you reach the outside ‘wall’ you are magically transported to the other side (like in Pac man). Why would this be the case when people have traveled to Antarctica and have not experienced this ‘Pac-man’ sensation? Also, the theory completely changes the ACCEPTED world map view. This would imply that the southern continents are a lot further away than traditionally thought. If this were true, the quickest way to get from South America to Australia would be to fly over the North Pole. Enough said.

The bottoms of clouds are flat

This is one of the principle arguments from flat earth theorists. Yes, some clouds have a flat bottom so in theory, this is a major challenge.

However, this can be explained by simple meteorology. Cumulus clouds (the puffy clouds that you’d recognise from children’s drawings) are created from pressure and temperature changes in the atmosphere. As water vapour moves upwards, the air expands due to a larger volume and a pressure drop. This height where cumulus clouds form is very specific and would appear to form a flat bottom due to the changes in our current atmosphere.

The Movement of the Sun

It is thought that the sun moves in circles around the North Pole and that during the day, the sun is over your head but during the night, the sun is away from you (kind of like a torch). The sun setting and rising is purely the perspective effect that the vanishing point of the sun. If you climb a mountain, the horizon rises according to your eye level and this is thought to be relevant in terms of the sunrise and sunset.

If the world was flat, we would be able to see the sun at all times because the curvature wouldn’t be there to prevent us from it. The only way to explain it is that there must be a complete other side otherwise we would never truly be in darkness.
Day/night cycle on a Flat Earth

Photos from NASA are a Conspiracy

It is thought that all photos of the globe have been edited to make us believe that the Earth is round. Flat earth conspiracists are not 100% sure why governmental agencies want to hide this but they potentially think it’s for financial gain of some sort.

For starters, why would NASA want to do this? Secondly, normal people (such as the video below) can prove that the Earth has a curvature.

The Moon and the Sun are the same size

They believe that the sun and the moon are the same in size, are 32 miles in diameter, and orbit around the North Pole.

This, again, is another argument from empiricism so if you looked up, it could be true. However, as you can also see, the moon is not always a circle. It goes through a cycle whereby the Earth’s shadow prevents us from seeing the full moon. This occurs as the sun is behind the Earth thus causing the shadow effect on the moon. Therefore, empiricism and basic physics can explain why the moon and the sun aren’t rotating around the North Pole. The sun also appears to be the same size as it’s located 149.6 million km away whereas the distance to the moon is only 384,400 km away so will appear to be the same as the sun is further away.

lunar eclipse

 

 

 

 

Gravity isn’t real, objects simply ‘fall’

According to flat earth theorists, gravity is an illusion and objects really just accelerate downwards. Apparently, this force is called ‘Universal Acceleration’  and that the density of objects is the reason they fall down.

Okay, this really doesn’t work. The thing with gravity is that with a sphere, wherever you are, there is the same amount of the sphere underneath you. This means that the gravitational pull is to the same point in the sphere. If the earth was flat, the center would have to pull towards the middle of the plane. This means that on each end, gravity would pull you sideways instead of downwards whereas, in the middle of the plane, you would actually be able to stand up straight.a sphere's center of mass

a plane's center of mass

 

 

 

But I can’t see any curvature?

Surely because ships disappear on our horizon, that means that they’ve reached that ice sheet right? 

You see, this argument is larger than just flat earth theory. If we relied on our senses when coming up with new theories and ideas, then most ideas would be completely unreliable. Our senses and empiricism would fail for flat earth theory because of how small humans are relative to the Earth itself. If we were to go on a hot air balloon ride, we would be able to see that our horizons literally expand. More scientifically, buying a high-pressure balloon and taping a camera onto it, you could see the ‘bigger picture’.  

So, do not rely on your senses to deduce the shape of the earth because if that was the case, my current world is just my bedroom window?

Here’s the proof:

 

If after these arguments you still are in disbelief then okay, maybe you can’t be convinced and should go back to basic science classes. But if you’ve been laughing at flat earth arguments like me, then welcome to science and the world of normalcy. Comment or send me an email if you have other arguments (I’d love to hear them) and then maybe I could write a post replying to those.

References:

Cover photo: Mic

Animation of day/night cycle: Flat Earth Society