Explain why the β carbon of an α,β-unsaturated carbonyl compound absorbs farther downfield...

Explain why the β carbon of an α,β-unsaturated carbonyl compound absorbs farther downfield In the 13C NMR spectrum than the a carbon, even though the α carbon is closer to the electron-withdrawing carbonyl group. For example, the β carbon of mesityl oxide absorbs at 150.5 ppm, while the α carbon absorbs at 122.5 ppm.