2.4: Weather (Paper 1 and 2)

Question 1

Explain the characteristics of a Stevenson Screen: (6)

Answer 1

• Made of wood because It is a bad conductor of heat. (1)
• It is painted white to reflect sun rays. (1)
• Has slates/louvres. To allow free circulation of air. (1)
• Has a double roof for insulation. (1)
• Placed 1.21m above the ground to avoid heat radiated from the ground. (1)
• The door of the screen faces South in the Southern hemisphere and North in the Northern hemisphere to avoid direct sunlight rays falling on the instruments when open. (1)

Question 2

Explain where a Stevenson Screen is located: (1)

Answer 2

• The screen is usually placed on a grass-covered surface, which reduces radiating ground heat. (1)

Question 3

Explain the use of a Stevenson Screen: (1)

Answer 3

• Providing shelter for meteorological instruments, particularly wet and dry bulb thermometers. (1)

Question 4

Explain how a rain gauge collects weather data: (3)

Answer 4

A rain gauge is used to measure rainfall. (1) It consists of a cylindrical container in which there is a collecting can containing a glass or plastic jar and a funnel that fits on top of the container. (1) It is important to check the rain gauge everyday particularly at the same time. (1)

Question 5

Explain how a six’s thermometer collects weather data: (6)

• Maximum Thermometer: (4)
• Minimum Thermometer: (2)

Answer 5

• Maximum Thermometer: When the temperature rises, the mercury expands and pushes the index along the tube. (1) When the temperature falls, the mercury contracts and the index remains behind. (1) The maximum temperature is obtained by reading the scale at the base of the index, which was in contact with the mercury. (1) The index is then drawn back to the mercury by a magnet. (1)
• Minimum Thermometer: When the temperature falls, the alcohol contracts and its meniscus pulls the index along the tube. (1) When temperature rises, the alcohol expands. (1)

Question 6

State the formula for finding the mean temperature: (1)

Answer 6

Mean Temperature = Maximum Temperature + Minimum Temperature/2 (1)

Question 7

Explain how a sunshine recorder collects weather data: (3)

Answer 7

• Make sure the paper (card or sheet) is inside. (1)
• The sun’s rays will scorch/burn the card. (1)
• At the end of the day, measure the length of the burn line, then convert to hours and finally calculate the time it was sunny. (1)

Question 8

Explain how a barometer collects weather data: (4)

Answer 8

A mercury barometer consists of a hollow tube from which the air is extracted before the open end is placed in a bath of mercury. (1) Mercury is forced up the tube by the pressure of the atmosphere on the mercury in the bath. (1) When the pressure of the mercury in the tube balances the pressure of air on the exposed mercury, the mercury in the tube stops rising. (1) The height of the column of mercury changes as air pressure changes. (1)

Question 9

Explain how an anemometer collects weather data: (5)

Answer 9

An anemometer is used to measure wind speed. (1) It consists of 3 or 4 metal cups fixed to metal arms that rotate freely on a vertical shaft. (1) When there is a wind, the cups rotate. (1) The stronger the wind, the faster the rotation. (1) The number of rotations is recorded on a meter to give the speed of wind in km/h. (1)

Question 10

Explain how a wind vane collects weather data: (5)

Answer 10

A wind vane is used to indicate wind direction. (1) It consists of a horizontal floating arm pivoted on a vertical shaft. (1) The rotating arm has a tail at one end and a pointer on the other. (1) When the wind blows, the arm swings until the pointer faces the wind. (1) The directions north, east, south and west are marked on arms that are rigidly fixed to the shaft. (1)

Question 11

Explain how a hand held digital anemometer collects weather data: (1)

Answer 11

The digital handheld anemometers need to be held into the oncoming wind and as the fan rotates, the number is shown on the screen. (1)

Question 12

Explain the characteristics of cirrus clouds: (3)

Answer 12

• High above 6km (1)
• Thin, white and made of ice crystals (1)
• Forms narrow wisps, thread and feathers. (1)
• Weather is fine (1)

Question 13

Explain the characteristics of cirrostratus clouds:(3)

Answer 13

• High above 6km (1)
• Thin, white layers of ice crystals with a wide, horizontal spread which often covers the whole sky. (1)
• Weather is fine. (1)

Question 14

Explain the characteristics of cirrocumulus clouds: (3)

Answer 14

• High above 6km (1)
• Thin, white heaped clouds with ice crystals. (1)
• Weather is fine (1)

Question 15

Explain the characteristics of altostratus clouds: (3)

Answer 15

• Medium 2-6km (1)
• Can be thin and white or grey and thick with layer of water droplets. (1)
• Weather is fine (1)

Question 16

Explain the characteristics of altocumulus clouds: (3)

Answer 16

• Medium 2-6km (1)
• Thick white, or grey looking heaped cloud of water droplets. (1)
• Weather is fine. (1)

Question 17

Explain the characteristics of stratus clouds: (3)

Answer 17

• Low 0-2km (1)
• Thin, uniform, grey sheet of small water water droplets with a fairly flat base. (1)
• Weather is fine drizzle. (1)

Question 18

Explain the characteristics of cumulus clouds: (4)

Answer 18

• Low 0-2km (1)
• White with a darker, flat base and a billowy upper surface. (1)
• Sunny by day fine weather. (1)

Question 19

Explain the characteristics of Stratocumulus clouds: (3)

Answer 19

• Low 0-2km (1)
• White and grey partly heaped clouds made of water droplets. (1)
• Weather is fine (1)

Question 20

Explain the characteristics of nimbostratus clouds: (3)

Answer 20

• Base can be low or above 2km. (1)
• Thick, dark grey layers of water droplets. (1)
• Steady rain or drizzle. (1)

Question 21

Explain the characteristics of cumulonimbus clouds: (3)

Answer 21

• Low base but usually extends to high levels. (1)
• Dense, dark grey clouds with vertical height. (1)
• Weather is very heavy rain, snow showers or hail with thunder and lightening. (1)

Question 22

Explain how cloud cover is measured. (2)

Answer 22

Cloud cover is measured in oktas. (1) This is made by a visual assessment of how much of the sky is covered by cloud. (1)

Question 23

Define the term isohyet: (1)

Answer 23

A line on a map which joins areas of equal rainfall. (1)

Question 24

Explain how a wet-dry bulb thermometer records weather data: (5)

Answer 24

Wet-dry bulb thermometers are used to measure relative humidity. (1) The dry-bulb is a glass thermometer which records the actual air temperature. (1) The wet-bulb is a similar thermometer, but with the bulb enclosed in a muslin bag which dips into a container of water. (1) The thermometer measures the wet-bulb thermometer in which the temperature is generally lower than the dry-bulb thermometer. (1) If both thermometers is the same, it means there is near 100% humidity. (1)