RH and Rain

What happens to air when it is hot?

• The air contracts, it can hold less water vapour.

• The air contracts, it can hold more water vapour.

• The air expands, it can hold less water vapour.

• The air expands, it can hold more water vapour.

What happens to air when it is cold?

• The air contracts, it can hold less water vapour.

• The air contracts, it can hold more water vapour.

• The air expands, it can hold less water vapour.

• The air expands, it can hold more water vapour.

What is the unit used to measure relative humidity?

• Mm

• %

• Degree Celcius

• Kg

When RH is 100%, it reaches saturation point. This is where water vapour condenses to become liquid water.

• True

• False

What is the relationship between temperature and RH?

• The higher the temperature, the higher the RH.

• The higher the temperature, the lower the RH.

• The lower the temperature, the higher the RH.

• The lower the temperature, the lower the RH.

Singapore typically experiences _________________ rain.

• Relief rain

• Convectional rain

• Orographic rain

• Frontal rain

Which of the following conditions is needed for convectional rain to form?

• Intense heat

• High humidity

• Near the coast

• High mountain

Which of the following conditions is needed for relief rain to form?

• Intense heat

• High humidity

• Near the coast

• High mountain

When humid air is forced up a mountain, the air warms up until it is saturated. It then condenses to form water droplets.

• True

• False

Answer explanation

When humid air is forced up a mountain, the air COOLS DOWN until it is saturated. It then condenses to form water droplets.

The side of the mountain that does not receive rain is called the _______ side.

• Windward side

• Leeward side