The warmest temperature occurs at _______ and why does the warmest daily temperature occur in mid-to-late afternoon rather than at the time if the highest sun angle?
The coolest temperature of the day occurs at sunrise. Why?
Sunrise
The warmest temperature occurs in the mid-to-late afternoon due to a combination of factors. To understand why, let's break it down step by step:
1. Solar Radiation: The sun releases solar radiation, which warms the Earth's surface. However, it takes time for the Earth's surface to absorb this radiation and heat up. Hence, the highest sun angle (around midday) does not instantly translate into the warmest temperature.
2. Diurnal Temperature Lag: Diurnal temperature lag refers to the delay between the peak solar radiation and the warmest temperature. It occurs because solar radiation continues to heat the Earth's surface even after the highest sun angle. This excess heat accumulates throughout the day and results in the warmest temperature occurring several hours later, typically in the mid-to-late afternoon.
3. Thermal Inertia: Another factor contributing to the warmest temperature occurring in the afternoon is thermal inertia. Thermal inertia refers to the property of materials (including the Earth's surface) to retain heat. During the day, the Earth's surface absorbs and stores thermal energy from the sun. This stored heat continues to release into the atmosphere, keeping the temperature elevated even after solar radiation diminishes.
Now, let's discuss why the coolest temperature of the day usually occurs at sunrise:
1. Radiative Cooling: During the night, with no sunlight, the Earth's surface emits longwave radiation (heat energy) back into space. This process is known as radiative cooling. As a result, the surface temperature gradually decreases during the night.
2. Longest Night: The coolest temperature generally occurs around sunrise because it marks the longest period of the night. Over the course of the night, the Earth's surface continuously cools down due to radiative cooling, reaching its lowest point just before sunrise.
In summary, the warmest temperature occurs in the mid-to-late afternoon due to factors like solar radiation, diurnal temperature lag, and thermal inertia. The coolest temperature of the day occurs at sunrise because it marks the end of the longest period of the night, during which radiative cooling has caused the surface temperature to drop.