Keith Kelly looks at examples of the language of line graphs from the area of science, covering rich idiom, verb, noun, adjective and adverbial phrases.

Phrases for upward movement

rise, grow, climb [+ steeply / rapidly / steadily / slowly / gradually] soar, rocket

  • Where the graph is rising steadily, the toy car has moved two metres in three seconds.
  • The line graph climbs gradually indicating a steady temperature rise over the two months data was collected.
  • The line grows steeply showing an increase in the amount of carbon dioxide in the test tube.

a slight / sharp increase, a steep rise
The speed-time graph shows a steep rise after three seconds.

have / experience a steady growth, show a steady / a gradual rise / increase

  • There has been a steady growth in world consumption of oil since the mid 1980s.
  • The gradual rise in the line graph indicates a steady increase in distance over time.

reach a plateau, show a wide / narrow peak

  • The line graph reaches a plateau at 74kg between 1993 and 1994, which indicates that that John’s weight stayed the same for that period.
  • Species one showed a peak of nearly ten flowers in bloom in the sixth week.

Phrases for movement up and down

fluctuate, [wild] fluctuations in
Despite fluctuations in world production of coarse grain, the overall trend is a steady increase in production for the period 1990 to 2000.

Phrases for downward movement

plunge, plummet
Species 1 and 2 plunged to their lowest point of less than one flower in bloom in week six.

drop, dip, bottom out

  • Despite an initial rise, the boys’ basketball team saw a gradual drop in the number of wins.
  • Finally, as the line dips the car moves back to its the point of origin.
  • The time-temperature line bottoms out in July for data for Christchurch, NZ.

fall steadily / considerably / sharply, quickly drop
The graph shows that world fertility rates are predicted to fall steadily to 2045.

a sharp / considerable / rapid drop, a steady fall, a slight dip

  • The graph shows a sharp drop in Space Station altitude from 385km to 330km in November 1999.
  • Though the graph shows a steady rise over the whole period, there are slight dips at 3.4, 5.3, and 7.6 seconds.

Phrases for level / stable movement

level off / out, flatten off / out

  • The line graph then levels out and this indicates that the car was stationary for four seconds.
  • The flat line shows that for the 12 months of the year the 24-hour average temperature remains constant in Quito.

Adverbs and adjectives

upward, downward
The line continues to move downward until it levels off and remains flat for the rest of the period.

slow but steady
The pulse rate returns slowly but steadily back to normal after exercise.

more or less
The accumulation of rubbish over the week is more or less constant.

The numbers of single females in China drops rapidly between the ages of 15 and 25.

Time phrases

in the first / third / last interval
The height of the tulip increases most of all during the last interval.

over the period / the year
There is a steady increase in height in relation to water provided over the entire period.