Understanding Weather Patterns and Process

What is Weather and its Elements

• Weather refers to the condition of the atmosphere at a specific time and place.
• Key elements of weather include: temperature, wind, humidity, precipitation and atmospheric pressure.
• These elements interact with each other and can change rapidly.
• These constant changes in weather are part of what meteorologists study to predict and understand weather patterns.

Temperature and its Factors

• Temperature is the measure of heat of the air.
• It varies with latitude, altitude, season, and time of day.
• Places at or near the equator tend to have higher temperatures than places near the poles because of direct sunlight.
• The temperature decreases with increasing altitude because air on higher altitudes is less dense and has less capacity to absorb and retain heat.

Humidity, Dew Point and Precipitation

• Humidity is the amount of water vapour in the atmosphere, which can influence weather patterns.
• When air at a certain temperature holds as much moisture as it can possibly hold, it is said to be saturated and has 100% relative humidity.
• The dew point is the temperature at which air becomes saturated, condensation occurs and can result in different forms of precipitation such as rain, snow, sleet or hail.
• Precipitation is a vital component of how water is recycled to our planet, and is one of the most frequently watched weather phenomena.

Atmospheric Pressure and Wind

• Atmospheric pressure is the force exerted by the weight of air in the atmosphere. Areas of high and low pressure are caused by ascending and descending air.
• As air warms, it rises leading to low pressure at the surface. As air cools, it sinks leading to high pressure at the surface.
• Wind is the movement of air from areas of high pressure to areas of low pressure. The greater the pressure difference, the faster the air flows.
• Winds can influence weather patterns and can transport heat and moisture from one place to another.

Types of Weather Patterns

• Certain weather patterns tend to recur over a specific region over time.
• One such pattern is the occurrence of seasons, which are caused by the tilt of the earth's axis and its orbit around the sun. The tilt of the axis and the orbit result in varying intensities and distributions of sunlight, causing winter, spring, summer, and autumn.
• Monsoon climates are characterised by alternation between wet and dry seasons. These are caused by the changing direction of prevailing winds.
• Other common weather patterns include stable weather associated with high-pressure systems and unstable weather with low-pressure systems.
• Unusually long periods of specific weather patterns may result in extreme weather events such as droughts, floods, heatwaves and cold spells.