Ch1 Global Hazards

What is atmospheric circulation?

Large scale movement of air by which heat is distributed on the earths surface

What is the Hadley cell?

Largest cell

extends from equator to 30° North and south

What is atmospheric circulation?

Large scale movement of air by which heat is distributed on the earths surface

What is the Hadley cell?

Largest cell

extends from equator to 30° North and south

What is the Ferrel cell?

Middle cell between 30° and 60°

What is the Polar Cell?

Smallest and weakest cell.

Extends between 60° and the poles

How are distinctive climate zones created?

Global circulation system controls temperatures, precipitation and prevailing winds.

What is temperate climate?

(Ferrel cell) Around 60° North and South of the equator.

Here air rises and cools forming clouds therefore frequent rainfall

What is the tropical climate?

(Hadley cell) Found along the equator.

Experiences heavy rain and thunderstorms.

What is the polar climate?

Within the polar zones

Cold air sinks causing dry and icy winds

What is sub tropical climate?

30° N and S of the equator

sinking dry air leads to high temperatures

without conditions for rainfall

How is High pressure belts formed?

Formed by cold air sinking

causes clear and calm weather

How are low pressure belts formed?

Caused by hot air rising

Causes stormy and cloudy weather

What are Katabatic winds?

Winds that carry air from high ground down a slope

What are trade winds?

Wind that blows from high pressure belts to low pressure belts

What are Jet streams?

Winds that are high in the atmosphere and rapid

What is precipitation?

When water vapour rises

It then cools as it rises and condenses into a cloud

Water molecules then become heavier and the water falls to earth as precipitation

What is convectional rainfall?

Air expands and rises

The rising air cools and condenses

Rain then falls

What is frontal rainfall?

When warm air and cool air meet, front is formed

The warm air rises over the cool air and clouds are produced

This produces rain

What is wind?

Movement of air from high pressure to low pressure

What is the El Nino effect?

Normally warm ocean currents cause moist warm air to rise and condense causing rain storms in Australia

In an El Nino year the cycle reverses. Cool water reverses the wind direction leading to dry sinking air over Australia causing hot weathers and droughts

How often is an El Nino year?

Every 5-7 years

Where do Tropical storms generally occur?

Places where sea temperatures rise above 27°C

How is a Tropical storm Formed/Created?

1. Sun rays heat the ocean causing warm air to rise over the ocean

2. The temperature hits 27°C and the Warm air rises forming low pressure. This cools and condenses and forms a thunderstorm.

3. Trade winds blow in the opposite direction and the earth’s rotation cause the thunderstorm to spin

4. When the storm spins faster than 74mph a tropical storm is born

5. More cool air sinks in the centre of the storm, called the eye of the storm

6. When the storm hits land it loses its energy source and typically lasts between 6-14days

What is the crust (Lithosphere)

35Km beneath land

made up of several large plates

What is the mantle?

Widest layer

Hear and pressure means the rock is in a semi liquid state

Convection currents operate here

What is the inner and outer core?

Hottest section

Very dense

Inner section is Solid, Outer layer is liquid

What is a destructive plate margin?

When the denser plate goes beneath the other, friction causes it to melt into magma

The Magma forces its way up to form a volcano

What is the constructive plate margin?

Two plates move apart causing new magma to reach the surface

Volcanos formed through this

What is the conservative plate margin?

caused by Plates sliding in opposite directions

responsible for earthquakes

what are collision zones?

Formed when two plates collide.

Both plates are forces up and form mountains

What are the types of volcanoes?

Shield

Composite

Hotspots

What is a shield volcano, and its eruption.

Made of basaltic rock and form cones

Eruption: Gentle and predictable

What is a composite Volcano and its eruption?

Created by layers of ash and lava

Eruptions: Explosive and unpredictable

How are earthquakes caused?

Two plates lock and cause friction build up

Pressure releases causing the plates to move

The movement causes energy in the form of seismic waves to travel from the focus to the epicentre.

The crust vibrates triggering an earthquake

How do you measure earthquakes?

Mercalli scale - Measures damages baes on observation. Limitations: Subjective

Richter scale - Scientific measurement based on energy released. Measured by seismometers. Uses measurements 1-10.

What are the hazards of Volcanos?

Ash cloud - Small pieces of rock thrown into the atmosphere

Gas - Sulphur dioxide and carbon dioxide are released

Lahar - Mudflow that runs down the volcano

Volcanic bomb - A think lava fragment that is ejected

What are the warning signs of a volcanic eruption and the monitoring techniques for the warning signs?

Small earthquakes are causes because of the Magma rise - seismometers to detect earthquakes

Temperature around the volcano increases- Thermal imaging can be used to detect heat around the volcano

What are the stages of earthquake management?

Prediction - seismometers to detect earthquakes and thermal imaging

Educating - earthquake drills and emergency supplies

Adapting buildings