The solar chromosphere

The temperature rises monotonically through the chromosphere, which is about 2500 km thick. The increase in temperature is very rapid at the boundary between the middle and high chromosphere and especially at the transition region between the chromosphere and corona. Typical transition-region models give a thickness of only 30 km for the rapid temperature rise from 3x104K to 3x105K and 2500 km for the slower rise from 2x105K to 106K. However, very little is known about the transition region and the objective of the spacecraft TRACE is to study the transition region. TRACE was launched on April 1, 1998.

Figure 1 shows a filament (prominence) in the chromosphere (in the south east part of the Sun) which disappeared on November 6, 1991 in association with a CME.

Figure 2 shows a prominence "Grand Daddy of June 4, 1946" on the solar limb.