Week 15 · Term 1 review (Units 1–2) and Darslab's own review tasks · 3 lessons
3
Review: the atmosphere and its protection
Integrated Science Sec 1 Term 1, Units 1–2: Review
GoalUse the ideas of Unit 2: layers, ozone, temperature scales, pressure, humidity, global warming, acid rain and monitoring.
New words
lapse rate · the fall of about 6.5 °C per km in the tropospheregreenhouse effect · gases holding part of the heat the surface sends outacid rain · rain made more acidic by dissolved SO₂ and NO₂ products
Explanation
This is a review: no new facts. Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon and 0.04% carbon dioxide. In the troposphere the temperature falls about 6.5 °C per km; it rises in the ozone layer (stratosphere), falls in the mesosphere and rises in the thermosphere. Ozone forms in two steps: O₂ + UV → O + O, then O + O₂ → O₃. CFCs thin the ozone layer and the Montreal Protocol limits them. t(°F) = 1.8 × t(°C) + 32. Heat moves by conduction, convection and radiation. Standard pressure is 1013 mbar = 760 mm of mercury; 1 mbar = 100 N/m². Wind blows from high to low pressure. Relative humidity = vapour ÷ most the air can hold × 100%. Burning fossil fuels adds greenhouse gases; SO₂ and NO₂ lead to acid rain; scrubbers remove them; satellites and weather stations monitor the air; climate models give ranges.
Layer
Temperature with height
troposphere
falls
stratosphere (ozone)
rises
mesosphere
falls
thermosphere
rises
Worked examples
The ground is at 22 °C. At 4 km the temperature is 22 − 4 × 6.5 = 22 − 26 = −4 °C.
Air holds 8 g of vapour per m³ and could hold 20 g. The relative humidity is 8 ÷ 20 × 100 = 40%, which is at the lower edge of the comfortable range of 40% to 60%.
Chain for global warming: burning fossil fuels, extra CO₂ and other greenhouse gases, more heat held in, a rise in the air temperature, ice melts and weather becomes more extreme.
Class activity
Atmosphere poster. On a large sheet draw the layers to scale with a strip (1 cm = 5 km), then add four labelled boxes: the ozone steps, the temperature rules, one pollution chain (SO₂ to acid rain) and one measuring tool. Present it to someone at home in one minute and ask them to find one thing they did not know.
Practice
1
The ground is at 18 °C. What is the temperature at 2 km?
18 − 2 × 6.5 = 18 − 13 = 5 °C.
2
Write the two steps of ozone formation.
O₂ + UV → O + O, then O + O₂ → O₃.
3
Convert 330 K to °C and 1013 mbar to N/m².
330 − 273 = 57 °C; 1013 × 100 = 101 300 N/m².
4
Place A has 1012 mbar and place B has 1004 mbar. Which way does the wind blow?
From A to B.
5
Name the gas that scrubbers do not remove, and one that they do.
They do not remove CO₂; they remove SO₂ (and nitrogen oxides).
