Climate patterns and extreme weather events can dramatically reshape our... Show more
Biology405 views·Updated Jun 4, 2026·2 pagesGlobal Weather Issues for CCEA AS Geography: EL NINO, LA NINA, and Hurricanes
1
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El Niño and La Niña: The Pacific's Weather Controllers
Ever wondered why some years bring unexpected droughts whilst others flood normally dry regions? The answer lies in the El Niño Southern Oscillation - a massive flip in Pacific Ocean currents that happens every 3-7 years.
During El Niño, warm ocean water flows east towards South America instead of west. This completely reverses the normal Walker Circulation pattern. Scientists define it as five consecutive months when ocean temperatures sit 0.5°C above average. The impacts are enormous - Southern Asia's vital monsoons weaken, affecting one in four people who depend on these seasonal rains.
La Niña creates the opposite effect, with temperatures 0.5°C below average for at least five months. Strong trade winds push warm water west, creating very low pressure over Australia and high pressure over South America. This intensifies normal weather patterns rather than reversing them.
Key Fact: The 1997-1998 El Niño caused 200 deaths and £9 billion in economic damage, showing just how powerful these cycles can be.
2
of 2
Hurricanes: Nature's Most Powerful Storms
Hurricanes are nature's ultimate weather machines, and understanding them could literally save your life. These low-pressure systems typically strike in late summer and early autumn when ocean temperatures peak above 26°C. They're measured on the Saffir-Simpson scale from 1-5, though they go by different names worldwide - cyclones in the Indian Ocean, typhoons in the South China Sea.
Hurricane formation requires specific conditions: warm ocean water at least 60-70 metres deep, uniform atmospheric conditions, and location between 5-30° north or south where the Coriolis force can create rotation. They start as easterly waves, develop into tropical depressions, then tropical storms, before reaching hurricane status with winds over 160 km/hr at the eyewall.
The structure is fascinating - a circular system 500-1000km wide with no weather fronts. The calm eye sits at the centre, surrounded by the violent eyewall where the strongest winds and heaviest rain occur. As hurricanes approach, temperatures and pressure drop rapidly, but when the eye passes overhead, you'll experience an eerie three-hour calm before the storm resumes with opposite wind directions.
Remember: Hurricanes move at just 25 km/hr but pack incredible destructive power, turning everyday objects like bins and furniture into deadly projectiles.
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Biology405 views·Updated Jun 4, 2026·2 pagesGlobal Weather Issues for CCEA AS Geography: EL NINO, LA NINA, and Hurricanes
Climate patterns and extreme weather events can dramatically reshape our world, affecting billions of people and entire economies. Two major phenomena - El Niño/La Niña cycles and hurricanes - demonstrate nature's incredible power to disrupt normal weather patterns and create... Show more
1
of 2Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
El Niño and La Niña: The Pacific's Weather Controllers
Ever wondered why some years bring unexpected droughts whilst others flood normally dry regions? The answer lies in the El Niño Southern Oscillation - a massive flip in Pacific Ocean currents that happens every 3-7 years.
During El Niño, warm ocean water flows east towards South America instead of west. This completely reverses the normal Walker Circulation pattern. Scientists define it as five consecutive months when ocean temperatures sit 0.5°C above average. The impacts are enormous - Southern Asia's vital monsoons weaken, affecting one in four people who depend on these seasonal rains.
La Niña creates the opposite effect, with temperatures 0.5°C below average for at least five months. Strong trade winds push warm water west, creating very low pressure over Australia and high pressure over South America. This intensifies normal weather patterns rather than reversing them.
Key Fact: The 1997-1998 El Niño caused 200 deaths and £9 billion in economic damage, showing just how powerful these cycles can be.
2
of 2Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Hurricanes: Nature's Most Powerful Storms
Hurricanes are nature's ultimate weather machines, and understanding them could literally save your life. These low-pressure systems typically strike in late summer and early autumn when ocean temperatures peak above 26°C. They're measured on the Saffir-Simpson scale from 1-5, though they go by different names worldwide - cyclones in the Indian Ocean, typhoons in the South China Sea.
Hurricane formation requires specific conditions: warm ocean water at least 60-70 metres deep, uniform atmospheric conditions, and location between 5-30° north or south where the Coriolis force can create rotation. They start as easterly waves, develop into tropical depressions, then tropical storms, before reaching hurricane status with winds over 160 km/hr at the eyewall.
The structure is fascinating - a circular system 500-1000km wide with no weather fronts. The calm eye sits at the centre, surrounded by the violent eyewall where the strongest winds and heaviest rain occur. As hurricanes approach, temperatures and pressure drop rapidly, but when the eye passes overhead, you'll experience an eerie three-hour calm before the storm resumes with opposite wind directions.
Remember: Hurricanes move at just 25 km/hr but pack incredible destructive power, turning everyday objects like bins and furniture into deadly projectiles.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content in Biology
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user