The absorption of solar light at or near the planetary surface increases the temperature gradient and may result in convection (a major process of cloud formation, often associated with precipitation).
Meteorological fronts are regions where the horizontal temperature gradient may reach relatively high values, as these are boundaries between air masses with rather distinct properties.
Clearly, the temperature gradient may change substantially in time, as a result of diurnal or seasonal heating and cooling for instance.
For instance, during the day the temperature at ground level may be cold while it's warmer up in the atmosphere.
As the day shifts over to night the temperature might drop rapidly while at other places on the land stay warmer or cooler at the same elevation.