Climate

The atmosphere

The global atmosphere moves as cells of rising and sinking air, and those cells make the winds and the rain belts.

CAPS

Grade 11 · Geography · Climate

Geography examines physical and human processes, with map skills in both papers.

  • The papers

    Paper 1 is climate and weather, and geomorphology, with geographical skills. Paper 2 is rural and urban settlement, and the economic geography of South Africa, with geographical skills. Each paper is 150 marks.

  • Map work

    Direction, scale, gradient, cross-section and a calculation from the map must show the formula and the substitution. A place you cannot point to on the extract is a guess.

  • How a marker reads it

    A common mix-up is to spin southern lows anticlockwise, the northern-hemisphere way, or to expect rain wherever there is a coast.

Paragraph questions want causes and effects in sequence. Naming a term without saying how it changes the landscape or the settlement is only the first mark.

layers

Diagram

Worked theory

Worked theory. The Namib and the equator. Air rises over the hot Congo basin and rain is heavy. The same air sinks over the west coast of southern Africa, so the Namib stays dry even though the sea is next door. Sinking air does not favour rain. On a winter synoptic chart, a low and its cold front cross the Cape. Ahead of the front the wind and the cloud change. Behind it the air is cooler. The chart is the cells and the fronts, drawn for Wednesday, not a new kind of atmosphere.

More worked examples

  • A July chart over Cape Town

    A low sits south-west of the Cape. Winds circle it clockwise. The cold front is the line with triangles. Ahead of it, north-westerly cloud and rain. Behind it, cooler air and showers. The Namib, under sinking air near 30 degrees south, stays dry on the same day. One chart, two parts of the same cells: rising air and a front at the Cape, sinking air on the desert coast.

  • A berg wind at the coast

    Air descends off the escarpment toward the coast, warms as it sinks, and arrives hot and dry. Relative humidity crashes. A fire that would have crept in moist air runs. This is not a cold front. A cold front brings cloud and a wind change from the north-west, then cooler air. The berg wind is the descending air. A forecast that says “it will be hot so a storm is coming” has mixed the berg wind up with convection.

In ordinary words

Warm air rises at the equator, travels poleward high up, sinks around 30 degrees, and returns as trade winds. That is the Hadley cell. Similar cells sit in the mid-latitudes and at the poles. Where air rises, rain is common. Where it sinks, deserts are common. The spinning Earth bends the winds. A synoptic chart draws the result for one day: highs, lows, and the fronts between warm and cold air. In the southern hemisphere, air circles clockwise into a low.

In South Africa

The dry Namib and a Cape winter front are the two African cases of this one atmosphere.

Part 1 / 4

What it is

The global atmosphere moves as cells of rising and sinking air, and those cells make the winds and the rain belts.

Diagram
Diagram
Diagram
Diagram

More worked examples

Board walkthroughs on this topic. Open one, copy the working, then try the next.

Example 1 / 20

Explain the formation of a coastal low pressure.

How we got there

Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.

Explain in another language · 11

1. What is the question asking?

Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Explain the formation of a coastal low pressure.

In other words — as if you have never seen this before

If you have never seen this before: Berg winds. We will name a method in words, write the formula with no numbers, then substitute one line at a time.

2. What do we already know?

Coastal lows.

3. Which method — and why this one?

Berg winds.

4. Step-by-step working

  1. 01 / 07

    Step A — Read the question twice

    Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  2. 02 / 07

    Step B — Write the given in a column

    Coastal lows.

    Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.

  3. 03 / 07

    Step C — Name the method in words

    Berg winds.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  4. 04 / 07

    Explain

    Forms on the west coast when offshore air flow (berg winds) creates low pressure along the coast; moves around the coast ahead of cold fronts.

    Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.

  5. 05 / 07

    Step G — Sense-check the size

    Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.

    Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.

  6. 06 / 07

    Step F — Box the answer with its unit

    Formed by offshore air movement.

    Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.

  7. 07 / 07

    Step H — What the marker is looking for

    On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.

    Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.

5. The answer

Formed by offshore air movement.

Copy onto your answer sheet — in this order

Answer: Formed by offshore air movement.

6. Check it like a marker

Brings hot dry weather.

7. A trap first-timers fall into

First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”

Ntsako · fx-991ZA PLUS. Tap to calculate.