Elements of weather
Weather is described by several measurable elements: temperature, rainfall, humidity, atmospheric pressure, and wind (speed and direction). Weather changes day to day; climate is the long-term average pattern of these elements for a region.
Climate types in Nigeria and West Africa
Southern Nigeria has an equatorial/tropical rainforest climate -- high temperatures and heavy rainfall year-round, with two rainy seasons. Moving north, the climate transitions to tropical savanna (wet and dry seasons clearly separated, less total rainfall), and finally to a semi-arid Sahel-type climate in the far north (low, unreliable rainfall and a long dry season).
Example 1: Explain why northern Nigeria receives less rainfall than southern Nigeria.
Southern Nigeria is closer to the coast and the equator, so moisture-laden winds from the Atlantic Ocean bring frequent, heavy rain. Northern Nigeria is further from the ocean's moisture source and more influenced by the dry, dust-laden harmattan winds from the Sahara, resulting in far less and less reliable rainfall.
Climate change
Climate change refers to long-term shifts in temperature and weather patterns, significantly accelerated by human activities like burning fossil fuels, which increase greenhouse gas concentrations in the atmosphere. Effects relevant to West Africa include shifting rainfall patterns, more frequent extreme weather, and desertification pressure at the Sahel's margins.