Unit 4: Synoptic maps

Question 1

What is a synoptic map?

Answer 1

It is a summary of weather conditions over a particular time

Question 2

Where is this information gathered?

Answer 2

From weather stations on Marion or Gough islands or airplanee, satellite images, weather balloons, floating weather buoys

Question 3

How often are the maps updated?

Answer 3

Every 6 hours

Question 4

How does air move in a high pressure cell?

Answer 4

The air descends (sinks) in an anti-clockwise direction while moving outwards (divergence)

Question 5

How does air move in a low pressure cell?

Answer 5

The air acsends (rises) in a clockwise direction while moving inwards (convergence)

Question 6

What is another name for a HP cell?

Answer 6

Anti-cyclone

Question 7

What is another name for a LP cell?

Answer 7

Cyclone or depression

Question 8

What are the names of the 3 HP cells that dominate SA?

Answer 8

South Atlantic high pressure cell, South Indian high pressure cell, Kalahari high pressure cell

Question 9

What is an isobar?

Answer 9

It is a line joining places of equal pressure at sea level

Question 10

What is air pressure measured in?

Answer 10

Hectopascals (hPa)

Question 11

What size the isobar interval?

Answer 11

4 hPa

Question 12

How is a trough formed?

Answer 12

When the isobars bend out around a LP cell

Question 13

How is a ridge/wedge formed

Answer 13

When the isobars bend out around a HP cell

Question 14

What is the area between two HP cells known as?

Answer 14

A saddle

Question 15

What are the symbols for the three types f fronts?

Answer 15

Cold front - a line with triangles
Warm front - a line with semi-circles
Occluded front - blue line with interchanging triangles and semi-circles

Question 16

What is an automatic station model represented by?

Answer 16

A circle in an triangle

Question 17

Weather symbols: rain

Answer 17

dot

Question 18

Weather symbols: drizzle

Answer 18

apostrophe

Question 19

Weather symbols: showers

Answer 19

upside down triangle

Question 20

Weather symbols: hail

Answer 20

triangle

Question 21

Weather symbols: snow

Answer 21

asterixis

Question 22

Weather symbols: thunderstorm

Answer 22

☈

Question 23

Weather symbols: fog

Answer 23

three horizontal lines

Question 24

Weather symbols: mist

Answer 24

two horizontal lines

Question 25

Weather symbols: tropical cyclone

Answer 25

6 and 9 combined

Question 26

What is the symbol for a normal station model?

Answer 26

a circle with a line pointing in the wind direction that has "feathers" that show the wind speed. On the left of this there is the maximum temperature then the type of precipitation then the dew point.

Question 27

How is wind direction named?

Answer 27

It is named according to the direction it blows from

Question 28

What is wind speed measured in?

Answer 28

Knots

Question 29

How is cloud cover shown?

Answer 29

⅛ - circle with a dot in the middle ²∕₈ - circle with a quarter outlined ⅜ - circle with a half outlined and cut in half ⁴∕₈ - circle half colored in ⅝ - circle with half colored in and a horizontal line ⁶∕₈ - circle with three quarters colored in ⅞ - fully colored in circle but with a square missing in the middle ⁸∕₈ or overcast - fully colored in circle Sky obscured by something other than clouds - circle with an x over it

Question 30

How is wind speed shown?

Answer 30

By the feathers on the end of the wind direction line ``` two circles - calm no feathers - 1-2 one short feather - 5 one long feather - 10 one short and one long feather - 15 two long feathers - 20 two long feathers and one short feather - 25 three long feathers - 30 triangle - 50 triangle, one long feather and one short feather - 65 ```

Question 31

What does a typical summer map look like?

Answer 31

Interior is dominated by a LP Trough Sub-tropical HP belt has shifted south There is a tropical cyclone off the east coast The frontal system are too far south to affect the weather of Western Cape Station models show higher temperatures The dates show summer months (Dec. - Feb.)

Question 32

What does a typical winter map look like?

Answer 32

Interior is dominated by a Kalahari HP Sub-tropical HP belt has shifted north Station models indicates clear skies over interior The frontal system are bringing rain to Cape Town Station models would show lower temperatures The dates show winter months (June - Aug.)