The day gets longer....

Right now, it's -15 deg C (5 deg F) outside. But, the season is changing quickly. We're up to 9 hours and 46 minutes of daytime, or six minutes more than yesterday. In a week and half, we'll have added a whole hour to the day. The effect of this daytime heating is apparent in the time series of temperature for the last 24 hours (see graph to the right, labeled in local time, where 00=midnight). We had a 6 degree C (about 10 deg F) change in temperature under full sunlight all day. Compare that to the time series from a cloud-free day back in December, when the temperature rise was barely 2 deg C under four hours less sunlight and a lower sun angle.