yAxisLabel = yAxis.append('text')
.attr('x', -dimensions.boundedHeight / 2)
.attr('y', -dimensions.marginLeft + 10)
.attr('fill', 'black')
.style('font-size', '1.4em')
.text('Relative Humidity')
.style('transform', 'rotate(-90deg)')
.style('text-anchor', 'middle')