IGCSE, Edexcel, IB and AP Science Courses | Dr Dabour Hub Academy

Overview

Understand the interrelations between the climate elements temperature, air pressure, wind, humidity and rainfall.
Distinguish the classifications of winds, the movements of air and the three genetic types of rain.
Analyse the causes of natural and environmental hazards and the greenhouse phenomenon.
Apply the lapse-rate rule to compute temperature at altitude.

Climate Elements, Air Pressure and Winds
├── First: the scientific terms (climate · weather · climatic region · pressure · hazards)
├── Second: the governing relations (temperature–pressure · lapse rate · Coriolis)
├── Third: the elements of climate and the atmosphere's interactions
├── Fourth: the five factors that differentiate temperature
├── Fifth: the pressure system and the four classes of wind
├── Sixth: the three genetic types of rainfall
├── Seventh: the great climatic regions of the Earth
├── Eighth: natural and environmental hazards
├── Worked examples
└── Exam traps

Lesson 3: Climate Elements, Air Pressure and Winds · 1 / 12

First: the scientific terms

Comparison aspect	Main idea	Keywords
Climate	the average state of the weather and the atmospheric regime of a given region over a long period — months seasons or years — in respect of temperature air pressure winds humidity and rainfall	averagestateweatheratmospheric
Weather	the state of the atmosphere at a specific place over a short period — one or two days a week at most — in respect of temperature humidity wind and rainfall	stateatmospherespecificplace
Climatic region	a defined continuous or discontinuous area of the Earth sharing climatic characteristics in temperature the timing of rain prevailing winds natural vegetation and wild life	definedcontinuousdiscontinuousarea
Air pressure and wind	air pressure is the weight of a column of air on a unit area of the surface winds move horizontally always from high-pressure areas toward low-pressure areas in accordance with Coriolis’ law	weightcolumnunitarea
Natural and environmental hazards	massive damage to environment and human beings caused either by natural phenomena with no human part in them (earthquakes volcanoes) or by destructive human interference (desertification global warming)	massivedamagehumanbeings

Lesson 3: Climate Elements, Air Pressure and Winds · 2 / 12

Second: the governing relations

Comparison aspect	Main idea	Example	Keywords
Inverse relation between temperature and pressure	rise in temperature → air expands and its density falls → low pressure. Warm air rises and creates a low cold air descends and creates a high	—	riseexpandsdensityfalls
Lapse rate with altitude	temperature falls 1 °C for every 150 m of rise above sea level — because the thickness of the atmosphere decreases. This explains snow on the peaks of equatorial mountains	Mount Kenya	temperaturefallseveryrise
Coriolis law	winds deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere because the Earth rotates on its axis from west to east. Sea currents deflect for the same reason	—	windsdeflectrightNorthern

Lesson 3: Climate Elements, Air Pressure and Winds · 3 / 12

Third: the elements of climate

Temperature is the most important element of all , because it is the active force behind every other element — pressure, wind, humidity and rain.
The Earth draws its heat and light entirely from solar radiation.
Temperatures differ from place to place on the globe, and the whole climate regime follows those differences.

Lesson 3: Climate Elements, Air Pressure and Winds · 4 / 12

Fourth: the five factors differentiating temperature

Comparison aspect	Main idea	Keywords
1. Position relative to the parallels of latitude	temperature rises the closer we are to the equator because sunlight falls vertically and crosses a shorter distance through the atmosphere it falls as we move north or south because the rays slant and scatter	temperaturerisescloserequator
2. Relief and altitude	temperature falls 1 °C per 150 m of elevation which explains permanent ice on high peaks inside hot tropical zones (Mount Kenya)	temperaturefallselevationexplains
3. Distance from water bodies	coastal regions are temperate in summer and warm in winter because water gains heat slowly and loses it slowly sea breezes moderate the temperature	coastalregionstemperatesummer
4. Vegetation cover	dense vegetation prevents direct sunlight from reaching the ground	densepreventsdirectsunlight
5. Length of day and night	days are long in summer so the Earth receives more solar radiation and temperature rises	dayslongsummerEarth

Lesson 3: Climate Elements, Air Pressure and Winds · 5 / 12

Fifth: the pressure system and the four classes of wind

Winds move horizontally permanently from high pressure to low pressure.

Class of wind	Behaviour	Examples
Permanent (planetary) winds	blow in a fixed system all year across the main pressure belts	Trade winds blow from latitude 30° toward the equator and temper the heat; the westerlies (reverse winds) are warm and rainy; the polar winds are extremely cold
Seasonal (monsoon) winds	reverse their direction seasonally between summer and winter	South and South-East Asia — rainy in summer, dry in winter
Local winds	blow over limited areas for short periods	Khamsin winds in Egypt, carrying dust in spring; Huboob in Sudan
Daily winds	caused by the temperature contrast between land and water by day and by night	sea breeze / land breeze and mountain / valley breeze

Lesson 3: Climate Elements, Air Pressure and Winds · 6 / 12

Sixth: the three genetic types of rainfall

Comparison aspect	Main idea	Keywords
•	Rain falls when water vapour rises and condenses in the cold upper layers of the atmosphere	Rainfallswatervapour
1. Convectional (rising) rain	hot moist air rises vertically cools condenses and falls heavy accompanied by thunderstorms — the rain of the equatorial zone	moistrisesverticallycools
2. Orographic (relief) rain	moist winds strike mountain slopes are forced up cool and rain on the windward slopes facing the sea the leeward side lies in the rain shadow	moistwindsstrikemountain
3. Cyclonic (frontal) rain	a cold air mass meets a warm moist air mass — the rain of the Mediterranean	coldmassmeetswarm

Lesson 3: Climate Elements, Air Pressure and Winds · 7 / 12

Seventh: the great climatic regions of the Earth

Comparison aspect	Main idea	Keywords
Hot regions	equatorial tropical savanna hot desert	equatorialtropicalsavannadesert
Warm temperate regions	the Mediterranean region — hot dry summer warm rainy winter on the west of the continents — and the Chinese region on the east rainy all year	Mediterraneansummerrainywinter
Cool temperate regions	as in western Europe	westernEurope
Cold regions	tundra and the mountain region	tundramountain
•	The details of each region its vegetation and its position in Egypt are treated in the next lesson	detailsregionvegetationposition

Lesson 3: Climate Elements, Air Pressure and Winds · 8 / 12

Eighth: natural and environmental hazards

Comparison aspect	Main idea	Keywords
1. Internal and natural hazards	born of hidden forces inside the Earth with no human part in causing them — earthquakes measured on the Richter scale and tsunami waves volcanoes which destroy villages yet increase the fertility of the soil	bornhiddenforcesinside
2. Environmental and climatic hazards	aggravated by unjust human activity — tropical spiral cyclones desertification caused by drought and overgrazing and global warming caused by greenhouse-gas emission which threatens melting of the polar ice a rise in sea level and the submergence of coastal deltas	aggravatedunjusthumanactivity

Lesson 3: Climate Elements, Air Pressure and Winds · 9 / 12

Worked examples

A mountain rises 3000 m above a foot at sea level where the temperature is 30 °C. What is the temperature at the summit, and does ice form?
- Total fall = 3000 ÷ 150 = 20 °C.
- Summit temperature = 30 − 20 = 10 °C.
- No ice forms, because 10 °C is above the freezing point — ice needs 0 °C or below.
Why is the daily temperature range larger in the desert than on the coast? — Because water gains and loses heat slowly and moderates the coast, while dry continental air heats fast by day and cools fast by night.
Give the reason snow falls on Mount Kenya although it lies near the equator. — The lapse rate of 1 °C per 150 m lowers the summit temperature below freezing despite the equatorial latitude.
A wind blowing from 30° N toward the equator is deflected which way? To the right (Northern Hemisphere), by Coriolis’ law.

Lesson 3: Climate Elements, Air Pressure and Winds · 10 / 12

Real-life applications

Khamsinwinds warn Egypt each spring: close windows, protect children and asthmatics from dust, and follow meteorological bulletins.

Cool temperate western Europerelies on the westerlies for its year-round rain, while Egypt’s north coast relies on cyclonic winter rain.

Agricultural planning follows the lapse ratehigh-altitude growing seasons are cooler and shorter, which is why greenhouse farming is used to offset climate.

Lesson 3: Climate Elements, Air Pressure and Winds · 11 / 12

Exam traps and key takeaways

💡 High-yield traps

Climate = long period; weather = short period. The distinction is a definition mark.
The lapse rate is 1 °C per 150 m, not per 100 m — the arithmetic question is built on that divisor.
Winds blow horizontally from high to low pressure; “from low to high” is the standard wrong option.
Coriolis right in the north, left in the south — caused by rotation from west to east.
Warm air rises → low; cold air descends → high. Do not say hot air creates a high.
Of the two latitudinal controls, the parallels of latitude are the important ones for climate.
Trade winds blow from 30° toward the equator; they are the ones that “temper the heat”.
Khamsin (Egypt) and Huboob (Sudan) are local winds; monsoons are seasonal; sea/land breeze is daily.
The three rain types are convectional, orographic, cyclonic — rain shadow belongs to the orographic explanation only.
Mediterranean rain is cyclonic and falls in winter; equatorial rain is convectional and heavy with thunderstorms.
Volcanoes are destructive but raise soil fertility — a frequent “which is FALSE” item.

Lesson 3: Climate Elements, Air Pressure and Winds · 12 / 12

Curriculum

Social Studies

Unit 1

Unit 2

Unit 3

Lesson 3: Climate Elements, Air Pressure and Winds