UNIT 1 : General atmospheric circulation
This course starts with an introduction to the primary or global atmospheric circulation which controls the climate. This section will explore the concepts of Tri-cellular circulation, Pressure belts and Planetary winds.
OBJECTIVE:
At the end of this section you will be able to identify cells in the tri-cellular arrangement, name the pressure belts and associated winds.
You will also be able explain how heat and moisture is distributed accross the globe.
You will be expected to anticipate potential threats of change in the atmospheric circulation to the earth's climate.
Prerequite concepts /Previous knowledge/Assumed knowledge
The unequal heating of the atmosphere, the significance of the Earth's axis and revolution around the Sun, the role of the winds and ocean currents in the transfer of energy
Materials and resources
a computer/tablet computer or smart phone connected to internet, earphones/headphones, hard copy notebook
Main Reader
Additinal resources ( a video )
Topic 1: General atmospheric circulation
This course starts with an introduction to the primary or global atmospheric circulation which controls the climate. This section will explore the concepts of Tri-cellular circulation, Pressure belts and Planetary winds.
OBJECTIVE:
At the end of this section you will be able to identify cells in the tri-cellular arrangement, name the pressure belts and associated winds.
You will also be able explain how heat and moisture is distributed accross the globe.
You will be expected to anticipate potential threats of change in the atmospheric circulation to the earth's climate.
Prerequite concepts /Previous knowledge/Assumed knowledge
The unequal heating of the atmosphere, the significance of the Earth's axis and revolution around the Sun, the role of the winds and ocean currents in the transfer of energy
Materials and resources
a computer/tablet computer or smart phone connected to internet, earphones/headphones, hard copy notebook
Main Reader
Additinal resources ( a video )
Topic 1: General atmospheric circulation
Incoming radiation from the Sun reaches the Earth unevenly. Because the Earth is spherical the amount of solar radiation recieved varies with distance from the Equator. More of incoming energy reaches the surface in the tropics than in the polar region. This unequal heating of the Earth's surface causes the global movement of the air by the wind. When the air is heated it becomes lighter and rises. The rising air causes law pressure. As the air cools down it becomes heavy and sinks. The sinking air causes a high pressure. The rising and sinking air caused by defferences in temperature and pressure causes the global circulation. The air circulates from higher pressure to lower pressure.
The global air circulation is made of :
The Hadley cell forms in the equatorial region due to high temperature at the Equator.
The Polar cell form in the polar region due to low temperatures in the North and South poles.
Ferrel cells are formed as a result of friction caused by the Hadly and Polar cells.
The global air circulation is made of :
- Tri-cellular cirulation
- Pressure belts
- Planetary wind
Tri-cellular cirulcation
The Hadley cell forms in the equatorial region due to high temperature at the Equator.
The Polar cell form in the polar region due to low temperatures in the North and South poles.
Ferrel cells are formed as a result of friction caused by the Hadly and Polar cells.
Pressure belts
There are four Pressure belts ; two low pressure belts resulting from the rising air and two high pressure belts resulting from the sinking air.
Air moves from high pressure belts to low pressure belts resulting in the global wind . Moving away from the Equator to the Pole the names of the four pressure belts are respectifully the Equatorial low pressure belt, Subtropical High Pressure belt, Subpollar Low Pressure belt and Polar High presser belt.
There are four Pressure belts ; two low pressure belts resulting from the rising air and two high pressure belts resulting from the sinking air.
Air moves from high pressure belts to low pressure belts resulting in the global wind . Moving away from the Equator to the Pole the names of the four pressure belts are respectifully the Equatorial low pressure belt, Subtropical High Pressure belt, Subpollar Low Pressure belt and Polar High presser belt.
Global winds/planetary winds
These are winds that cover large areas over the Earth’s surface. There are
three global wind systems:
• The tropical easterlies
• The westerlies
• The polar easterlies
The tri-cellular arrangement, the pressure belts and the global winds
together form the global air circulation
These are winds that cover large areas over the Earth’s surface. There are
three global wind systems:
• The tropical easterlies
• The westerlies
• The polar easterlies
The tri-cellular arrangement, the pressure belts and the global winds
together form the global air circulation
Atmospheric circulation leads to transports of heat and moisture accross the globe.
Change in the atmospheric circulation is an indication of climate change.
Change in atmospheric circulation occurs as a result of poleward displacement
There can be tropical circulation change due to poleward expansion of the hardly cells. There can also be extratropical circulation change due to poleward shift of the zone of high westerly winds in the midlatitudes.
Unit 1 Assessment: Click here to take the quizz
Change in the atmospheric circulation is an indication of climate change.
Change in atmospheric circulation occurs as a result of poleward displacement
There can be tropical circulation change due to poleward expansion of the hardly cells. There can also be extratropical circulation change due to poleward shift of the zone of high westerly winds in the midlatitudes.
Unit 1 Assessment: Click here to take the quizz