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