2.4 - Weather

Question 1

What is a Stevenson screen?

Answer 1

a small weather station that is used to measure local weather conditions

Question 2

What are some features of a Stevenson screen?

Answer 2

-white (reflects sun rays)
-wood reduces heat conduction/absorption
-air slats (for ventilation)
-raised 1.25m above ground (avoid strong temperature gradients at ground level)
-locked (stops people tampering with equipment)

(WWARL)

Question 3

Why are thermometers and wet/dry bulb thermometers left inside Stevenson screens?

Answer 3

-makes sure direct/absorbed sunlight doesn’t affect readings (white coating reflects it)
-free flow of air ventilation
-not affected by radiation from ground
-secure from tampering

Question 4

Where should a Stevenson screen be placed?

Answer 4

-away from buildings/trees (prevents wind blockage)
-on grass, not concrete (it gets too hot otherwise)
-face north in NH (stops direct sunlight when opened)

Question 5

What does a rain gauge measure? Where is it placed?

Answer 5

rainfall (always in an overflow cylinder in open area)

Question 6

What does a max. min. thermometer measure? How do you read one?

Answer 6

temperature range (read bottom of markers)

Question 7

What does a hygrometer/wet dry bulb thermometer measure?

Answer 7

relative (%) humidity (larger difference means lower humidity)

Question 8

What does a sunshine recorder measure?

Answer 8

hours of sunshine (focused sun burns into a single-use time card)

Question 9

What does a barometer measure?

Answer 9

air pressure

Question 10

What does an anemometer measure?

Answer 10

wind speed

Question 11

What does a wind vane measure?

Answer 11

wind direction
(points in the direction where the wind originates)

Question 12

Give some advantages of digital measuring instruments:

Answer 12

-more accurate + precise
-easier to read, no human error
-faster to read, saves time

-linked to computer to log data (can be left for longer periods without human monitoring/transferring data)

Question 13

Give some disadvantages of digital measuring instruments:

Answer 13

-could be damaged by weather
-needs power (limits the location of usage)
-more expensive (don’t say this unless desperate, they are actually cheaper nowadays)

Question 14

How do you assess cloud cover?

Answer 14

-choose a set time of day and location to check sky
-check the same area of sky every day at that time over several weeks/months
-look up at sky, hold rectangle at arm’s length
-estimate cloud cover in oktas
-cloud types (identify using diagram/chart/book)
-record in table

Question 15

Describe what a cirrus cloud looks like:

Answer 15

-high altitude
-long, thin and wispy
-made of ice crystals

Question 16

Describe what a cumulus cloud looks like:

Answer 16

-mid altitude
-white + fluffy
-flat base
-broken up/discontinuous

(if you get cumulus clouds in the morning, there will usually be rain later in the day)

Question 17

Describe what a stratus cloud looks like:

Answer 17

-low altitude
-grey + fuzzy
-covers most of sky

can also form fog

Question 18

What are the names of tropical storms in different locations?

Answer 18

-hurricanes (N. America)
-cyclones (India/Australia)
-typhoons (Japan)

Question 19

What are the formation requirements for a tropical storm?

Answer 19

-need >26°C water (evaporating water fuels storm, usually found near equator)
-need >74mph winds (to be classed as a hurricane on Saffir Simpson scale)

Question 20

Describe the ideal location for a wind vane:

Answer 20

-high up on a building
-in an open space
-clear from obstructions like a tree or building

Question 21

How is data collected and recorded at a digital weather station?

Answer 21

-connected to data loggers and a computer to automatically record things
-no human interference needed

Question 22

Name 4 instruments that may be found in a Stevenson screen:

Answer 22

-thermometer
-max-min thermometer
-hygrometer
-barometer