Climate GI Answers 21st Sep

1	A group of students recorded the temperature and relative humidity every hour for twelve hours. Study Fig. 1 which shows the readings.
	(a)	Name the instrument that is used to collect the readings for relative humidity.               [1] ·       Award [1] Sling Psychrometer ·       Award [0.5] Psychrometer
	(c)	Suggest two factors that can cause the data collected for relative humidity to be inaccurate.                                                                                                                        [2] ·       Swinging the psychrometer too near the body [0.5] which picks up body heat. [0.5] ·       Wrong reading of the temperatures on the thermometers. ·       Swinging the psychrometer for too long/short (time) [0.5] which affects the evaporation rate of the temperature. [0.5] (Accept any other possible answers)
	(e)	Suggest the relationship between temperature and relative humidity using the graph created in 1(d).                                                                                                                 [1] Inverse relationship / relative humidity decreases when temperature increases / Relative Humidity increases when temperature decreases

2015 Class test

1	Students at a school in Singapore went to Gardens by the Bay in December to record temperature, rainfall and wind speed at 2pm every day for six days. The readings are shown in Fig. 1 below. Day Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Mean temperature (°C) 27.5 27.5 27.5 27.5 25 25 Rainfall (mm) 20 20 0 0 10 10 Wind speed (m/s) 2 2 2 2 2 2
	(b)	The students were testing the hypothesis ‘More rainfall is collected when the mean temperature is lower.’ How far do the readings in Fig. 1 support this hypothesis? The readings do not support the hypothesis. When the mean temperature is higher (27.5°C) on day 1 and 2, the rainfall is higher (20mm). When the mean temperature is lower on day 5 and 6 (25°C) the rainfall is lower (10mm). *** Award max 2m if data is not used.
	(c)	Describe the techniques the students could take to ensure that wind speed is obtained as accurate as possible.
		Select a location in an open area that is on high level. Place the anemometer where the wind is blowing directly at it for at least 5 seconds. Maintain the position of the anemometer. Collect three readings and find the average. *** Accept any 4 points.
	(d)	The students calculated the mean temperatures shown in Fig. 1 by taking the maximum and minimum temperatures at Gardens by the Bay. Suggest two possible reasons for the variations in their readings.
		Occurrence of human errors in reading and recording maximum and minimum temperature from the maximum and minimum thermometer. Students may be taking temperature at different spots at Gardens by the Bay that may have different type of land surface such as concrete and grassy ground, which may affect the readings. Students may be taking temperature at indoor or outdoor spots that cause temperature to vary greatly. *** Accept any plausible answer with explanation.