Statement 1 is not correct: Jet streams occur in both the Northern and Southern Hemispheres. The actual appearance of jet streams result from the complex interaction between many variables - such as the location of high and low pressure systems, warm and cold air, and seasonal changes. Statement 2 is correct: The hurricane's center is a relatively calm, generally clear area of sinking air and light winds that usually do not exceed 15 mph (24 km/h) and is typically 20-40 miles (32-64 km) across. An eye will usually develop when the maximum sustained wind speeds go above 74 mph (119 km/h) and is the calmest part of the storm. Statement 3 is not correct: The eye is the region of lowest surface pressure and warmest temperatures aloft - the eye temperature may be 10°C warmer or more at an altitude of 12 km than the surrounding environment, but only 0-2°C warmer at the surface in the tropical cyclone.