'It is a fantastic view from the top.'
'Better be,'gasped Joe. 'How much further from there?'
'The river? A long way yet.'
A gust of wind waved the bracken across the track- a brief cooling.
'Often springs up in the afternoon,' said Peggy. 'Gets quite fresh sometimes.'
'Feels good,' said Joe.
In the above paragraph, what does 'springs up' refer to? Is it the air that springs up or the river springs up?
I am trying to read English short story and I do not understand that part. Can you help me? Thank you.