Why is the sun warmer in the summer?

During summer months, the part of the world having summer is close to a right angle to the rays of the sun, giving the most heat to the area exposed. During winter, the tilt of the earth means the sun's rays strike the earth at an angle, meaning that they spread over a larger area, giving less heat. When it is summer in the northern half of the world, it is winter in the southern half. Temperature difference is not due to distance from the sun, but due to the tilt of the earth. If distance was the determining factor, both north and south would be the same temperature.