The angle of the Earth, which is 23.5 degree's always does not change, it simply moves in it's orbit and becomes orientated differentely. Also, the Earth is at perigee during winter and the relation or the distance from the sun has nothing to do with the season, it has to do with the angle of insolation (incoming solar radiation). The way the earth is orientated effects how sunlight is recieved at the earth's surface, generally the greater the angle the more insolation recieved, this indirectly effects the placement of the ITCZ which is the convergence zone that spawns tropical waves, SST's and many more things.
well, that's not exactly right. the milkanovitch cycle and a more or less elliptical path around the sun affect the global heat budget to a large degree over their thousands of years worth of phase. the degree of dynamism and systemic redundancy, built in stability regimes.. make the world a good bit more robust and able to withstand change than a lot of global warming pundits would make mention of. -HF