(i) Delhi experiences rain in December- January due to western disturbances which originate in areas near the Mediterranean Sea. The western disturbances move under the influence of westerly jet stream and bring rain in northern and northwestern parts of India during this time.
(ii) Kolkata has little rain in April due to Norwesters thunderstorms. The sudden contact between dry and moist air causes this storm condition also known as Kalbaisakhi in the month of April-May.
