1.3 Weather Hazards Flashcards
Wind
The movement of air on a large scale
The air is made up of a mixture of gases
What causes wind
Differences in air pressure cause winds
What changes air pressure
Different temperatures cause movement like with convection currents
The equator is warmer than the North Pole or the South Pole
This difference causes different air pressures
Where does wind move in terms of air-pressure
Winds move from high-pressure areas of the Earth to lower-pressure areas of the Earth
Trade winds
Surface winds that blow from 30° north or 30° south back towards the equator
In the southern hemisphere, trade winds will blow from south-east to north-west until they reach the equator
In the northern hemisphere, trade winds blow from north-east to south-west until they reach the equator
Trade winds from the northern & southern hemisphere meet at the equator, where they are heated and the cycle begins again
Westerlies
Surface winds that blow from 30° north towards the North Pole or from 30° south out towards the South Pole
In the southern hemisphere, westerlies blow from north-west to south-east until they reach the South Pole
In the northern hemisphere, westerlies blow from south-west to north-east until they reach the North Pole
Global atmospheric circulation
Describes how air circulates between low and high-pressure belts as a result of differing conditions at different latitudes
This involves the transfer of heat via circulation cells
The equator
The Earth’s surface is warmed by the Sun at the equator
The Earth transmits this heat to the nearby air
This air gets hotter and rises. The rising, hot air forms a low-pressure belt. As the hot air rises, the air will begin to cool, with water vapour condensing, creating rain and clouds
The rising air cools and moves away from the equator towards 30o north and 30o south
30o north and south
The air is further from the equator and the cool air falls
This results in a high-pressure belt with minimal rainfall and no clouds
When the cool air reaches the Earth’s surface, surface winds blow the cool air either towards the equator, or away from the equator towards the Poles
60o north and south
At 60° north and south, cold air blown from the poles meets warm air surface winds
Because the warmer air is less dense, it rises and forms a low-pressure belt
The air splits, with some returning back towards the equator and the rest heading to the poles
The poles
At the North Pole and the South Pole, cool air will sink, forming a high-pressure belt
This high-pressure belt will move back towards the Earth’s equator as a surface wind
What are tropical storms
Very intense low-pressure weather systems
Have extreme rain and extreme winds
What are tropical storms called in North America
Hurricanes
What are tropical storms called in the Indian ocean
Cyclones
What are tropical storms called in south-east Asia
Typhoons
What are tropical storms called in Australia
Willy willy
In what conditions do tropical storms form
Tropical storms form over water that is 26.5oC or warmer and when there’s a small difference in wind speeds between the upper atmosphere and the lower atmosphere
When do tropical storms form
Tropical storms form over water that is 26.5oC or warmer
Lots and lots of energy is released when air evaporates, rises or cools. This increases the speed and energy of a storm
The strength of a storm falls as they move further away from warm water (so when storms are above land or above cooler parts of the ocean)
Why do tropical storms move west
Near the equator, surface winds are mainly trade winds moving east
The trade winds and the Coriolis Effect means that tropical storms move from east to west
Hows does spin affect tropical storms
The rotation of the Earth causes the Coriolis effect, which makes tropical storms spin by deflecting winds
Storms spin anticlockwise in the northern hemisphere
Storms spin clockwise in the southern hemisphere
Features of tropical storms: eye
Descending air, low pressure, no clouds, rain or wind, high temperature
What are the features of a tropical storm’s eyewall
Rising air, very strong winds, storm clouds, torrential rain, low temperature
What are the features of a tropical storm’s edge
Smaller, scattered clouds, less rain, rise in temperature, winds speed falls
Features of tropical storms
Circular shape
Hundred of kilometers wide
Last 1-2 weeks
Structure of tropical storms
A storm’s centre is known as the eye of the storm
Cool air descending from the eyewall creates the eye of the storm, which can be 50km wide
In the eye, there is no rain and low pressure (and a warmer ground temperature)
The eyewall surrounds all sides of the eye of the storm
In the eyewall, hot air rises, winds are very strong and there is a lot of rain
At the edges of storms, conditions are intermediate: wind speeds, rain intensity and temperatures are moderate, and clouds are small and scattered
Effects of climate change on storms: Distribution
Climate change is expected to lead to increases in temperatures
Currently, most tropical storms happen close to the equator, where the sea temperature is above 26.5oC
More of Earth’s seas will be warmer than 26.5oC, so there will be more storms and those that happen will have more energy
How does climate change affect the frequency of tropical storms
Oceans will be warmer than 26.5°C, so the frequency of storms will rise and storm season will get longer
The number of storms varies a lot, but warmer seas will lead to more storms
How does climate change affect the intensity of tropical storms
The higher the temperatures of the oceans, the more energy tropical storms will accumulate, the greater the intensity of the storm
More intense storms will cause more damage to buildings, infrastructure, and people
What are the primary effect of tropical storms
Damage to infrastructure - transport networks, railway lines, roads, and bridges can be damaged or flooded
Flights and train journeys are often cancelled because high winds make travel dangerous
Flying debris blown by the winds can kill or injure people
Electricity cables and pylons above ground can be damaged by wind or debris
Rivers and coastal towns can be flooded and the water damage can last for years
Floods can also cause sewage to overflow out of drains, potentially mixing with water supplies
What are the secondary effects of tropical storms
Floods can damage people’s houses causing homelessness. Without finding shelter, people could freeze to death outside
If water or electricity supplies are cut off, people can become isolated and stranded from basic health requirements. This can cause illness and viruses to spread
People may not be able to get work and earn money if airports and train lines are damaged
Damaged roads, airports, and train lines could stop aid and emergency services helping those affected
Damage to crops, the death of livestock, and the blocking of supply lines can all contribute to food shortages
Reducing the effects of tropical storms: Prediction
Scientists can monitor storms using satellites, planes, and innovations like radar
Meteorologists build models to try to forecast the weather and cyclones. However, the weather is very complicated and accurate prediction a long time in advance is very difficult
How does protection reduce the effects of tropical storms
Planning regulations on buildings and construction can ensure that buildings are built safely and only in areas that are unlikely to be flooded or damaged by hurricanes
Stilts are used in some nations to help stop flooding. Reinforced concrete is a stronger material that is better protected against floods
Flood defences can be constructed in vulnerable areas
How does planning reduce the effects of tropical storms
Firefighters and ambulances should receive specific disaster training
The 1st of September is Japan’s National Disaster Preparation Day
Special plans for evacuation and rescue could save lives
Weather in the UK: Heatwaves
Heatwaves are extended periods of hot weather
If heatwaves go on too long, it can lead to periods of drought, like in Cape Town in 2019
Humans and animals can suffer from heat exhaustion and transport links can also be disrupted as rails buckle and the tarmac on roads melts
Trains often have to limit their speed to 50mph in very hot conditions
Weather in the UK: Droughts
Drought happens when an area does not get enough precipitation
Water supplies and reservoirs can dry up
This can lead to a lack of drinking water and crop failures if there is not enough irrigation
The UK government sometimes introduces hosepipe bans to preserve water in these situations
Weather in the UK: Rain
Cardiff is the UK’s wettest city, with 115cm of rain each year
If there is too much rainfall, areas can flood. In 2004, Boscastle town in Cornwall flooded after heavy rain
People can be trapped in their homes, the foundations of houses can be damaged and people can drown
Repairing flood damage is very expensive and houses on areas vulnerable to flooding can be impossible to insure
Weather in the UK: Ice and snow
Slipping on ice can cause head injuries that kill some people
Homeless people are particularly vulnerable to the cold and many die in the winter each year
If there is too much snow, businesses may be forced to shut, along with schools, railway lines, roads, and airports
Harsh, cold winters and kill crops or reduce crop yields, causing problems for farmers, and potentially causing food shortages
Weather in the UK: Wind
Wind in the UK is rarely as strong as Hurricane Patricia’s 345km/h winds
However, Storm Ciara and Storm Dennis in 2020 caused the UK’s Avanti railway lines and airports like Heathrow to cancel flights
Many areas in Yorkshire and Wales were flooded and people were killed by falling trees
The UK coast and upland regions suffer from the strongest winds in the UK
Weather in the UK: Hail and thunderstorms
Cyclones are rare in the UK
Thunderstorms with torrential rain, thunder and lightning are more common
During the summer, hailstorms are possible
Hailstones fall and they can break windows and reduce visibility on roads, potentially causing injuries
Changing weather in the UK: Temperature
The UK’s 10 hottest years on record (since 1884) have all been since 2002
The winter of 2010-2011 was the coldest winter since early records in 1659
Changing weather int eh UK: Rain
December 2015 was the wettest month on record in the UK and temperatures were 4.1 degrees celsius higher than average for December
Changing weather in the UK: Flooding
Storms and heavy rainfall have led to major flooding in:
Boscastle (2004)
South Wales (2020 - Storm Ciara & Storm Dennis)
West Wales (2012)
Cumbria (2005, 2009 and 2015)
