1A - Weather Hazards Flashcards
What does global atmospheric circulation cause?
Causes ares to have some types of weather more than other - affect earth’s climate
What are winds essentially?
Are large scale movements of air caused by differences in air pressure
What are differences in air pressure caused by?
Differences in temperature between equator and poles
Winds move from areas of … to areas of …
Winds move FROM the areas high pressure TO the areas of low pressure
What are winds parts of?
Winds are parts of global atmospheric circulation loops (or cells)
What are 2 things global atmospheric circulation loops have and what do they create?
- Warm rising air = creates low pressure belt
2. `Cool falling air = creates high pressure belt
How many loops are in each hemisphere?
3
Global Atmospheric Circulation: Describe stage 1 - at the equator
- At the equator, the sun warms the Earth = transfers heat to air above = causing it to rise
- This creates low pressure belt with rising air, clouds and rain
Global Atmospheric Circulation: Describe stage 2 - as the air cools
As air rises it cools and moves out 30° north and south of equator
Global Atmospheric Circulation: Describe stage 3 - at 30° north and south of equator
At 30° north and south of equator, cool air sinks = creating high pressure belt with cloudless skies and very low rainfall
Global Atmospheric Circulation: Describe stage 4 - as cool air reaches ground surfaces
Cool air reaches ground surfaces and moves as surface winds either back to equator or towards poles
What are trade winds?
Surface winds blowing towards equator
What do trade winds do?
They blow from SE in southern hemisphere and from NE in northern hemisphere
What are westerlies?
Surface winds blowing towards poles
What do westerlies do?
They blow from NW in southern hemisphere and from SW in northern hemisphere
At the equator, what happens to trade winds & what does this cause them to do?
These trade winds meet and are heated by sun causes them to rise and form clouds
Global Atmospheric Circulation: Describe stage 5 - at 60° north and south of equator
- 60° north and south of equator the warmer surface winds meet colder air from poles
- Warm air is less dense than cold air so it rises, creating low pressure
Global Atmospheric Circulation: Describe stage 6 - some of the air moves
Some of air moves back towards equator, rest moves towards poles
Global Atmospheric Circulation: Describe stage 7 - at poles cool air
- At poles cool air skins, creating high pressure
- High pressure air is drawn back towards equator as surface winds
What are tropical storms?
Intense low pressure weather systems with heavy rain and strong winds that spiral around the centre
Give 3 names that tropical storms are known as
Hurricanes, typhoons and cyclones
When do tropical storms develop (give 2 conditions)
- When sea temperature is 27°C or higher (warm)
- When wind shear between higher and lower parts of atmosphere is low
What is wind shear?
The difference in wind speed
What makes a tropical storm powerful?
The amount energy it releases which comes from warm, moist air rising and condensation occurring
What does rising air create?
Rising air creates an area of low pressure, increases surface winds
Why do tropical storms move towards west?
Because of easterly winds near equator